diff --git a/engine/src/flutter/fml/BUILD.gn b/engine/src/flutter/fml/BUILD.gn
index ab34374913..e81ed4f168 100644
--- a/engine/src/flutter/fml/BUILD.gn
+++ b/engine/src/flutter/fml/BUILD.gn
@@ -8,6 +8,9 @@ source_set("fml") {
     "icu_util.h",
     "mapping.cc",
     "mapping.h",
+    "memory/weak_ptr.h",
+    "memory/weak_ptr_internal.cc",
+    "memory/weak_ptr_internal.h",
     "message_loop.cc",
     "message_loop.h",
     "message_loop_impl.cc",
@@ -24,8 +27,8 @@ source_set("fml") {
   ]
 
   deps = [
-    "//third_party/dart/runtime:dart_api",
     "//garnet/public/lib/fxl",
+    "//third_party/dart/runtime:dart_api",
 
     # These need to be in sync with the Fuchsia buildroot.
     "//third_party/icu",
@@ -33,9 +36,7 @@ source_set("fml") {
 
   configs += [ "//third_party/icu:icu_config" ]
 
-  public_configs = [
-    "$flutter_root:config",
-  ]
+  public_configs = [ "$flutter_root:config" ]
 
   libs = []
 
@@ -108,15 +109,16 @@ executable("fml_unittests") {
   testonly = true
 
   sources = [
+    "memory/weak_ptr_unittest.cc",
     "message_loop_unittests.cc",
     "thread_local_unittests.cc",
     "thread_unittests.cc",
   ]
 
   deps = [
-    "//third_party/dart/runtime:libdart_jit",
     "$flutter_root/fml",
     "$flutter_root/testing",
     "//garnet/public/lib/fxl",
+    "//third_party/dart/runtime:libdart_jit",
   ]
 }
diff --git a/engine/src/flutter/fml/memory/weak_ptr.h b/engine/src/flutter/fml/memory/weak_ptr.h
new file mode 100644
index 0000000000..5b85c53196
--- /dev/null
+++ b/engine/src/flutter/fml/memory/weak_ptr.h
@@ -0,0 +1,178 @@
+// Copyright 2016 The Fuchsia Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// This file provides weak pointers and weak pointer factories that work like
+// Chromium's |base::WeakPtr<T>| and |base::WeakPtrFactory<T>|.
+
+#ifndef FLUTTER_FML_MEMORY_WEAK_PTR_H_
+#define FLUTTER_FML_MEMORY_WEAK_PTR_H_
+
+#include <utility>
+
+#include "flutter/fml/memory/weak_ptr_internal.h"
+#include "lib/fxl/logging.h"
+#include "lib/fxl/memory/ref_counted.h"
+
+namespace fml {
+
+// Forward declaration, so |WeakPtr<T>| can friend it.
+template <typename T>
+class WeakPtrFactory;
+
+// Class for "weak pointers" that can be invalidated. Valid weak pointers can
+// only originate from a |WeakPtrFactory| (see below), though weak pointers are
+// copyable and movable.
+//
+// Weak pointers are not in general thread-safe. They may only be *used* on a
+// single thread, namely the same thread as the "originating" |WeakPtrFactory|
+// (which can invalidate the weak pointers that it generates).
+//
+// However, weak pointers may be passed to other threads, reset on other
+// threads, or destroyed on other threads. They may also be reassigned on other
+// threads (in which case they should then only be used on the thread
+// corresponding to the new "originating" |WeakPtrFactory|).
+template <typename T>
+class WeakPtr {
+ public:
+  WeakPtr() : ptr_(nullptr) {}
+
+  // Copy constructor.
+  WeakPtr(const WeakPtr<T>& r) = default;
+
+  template <typename U>
+  WeakPtr(const WeakPtr<U>& r) : ptr_(r.ptr_), flag_(r.flag_) {}
+
+  // Move constructor.
+  WeakPtr(WeakPtr<T>&& r) = default;
+
+  template <typename U>
+  WeakPtr(WeakPtr<U>&& r) : ptr_(r.ptr_), flag_(std::move(r.flag_)) {}
+
+  ~WeakPtr() = default;
+
+  // The following methods are thread-friendly, in the sense that they may be
+  // called subject to additional synchronization.
+
+  // Copy assignment.
+  WeakPtr<T>& operator=(const WeakPtr<T>& r) = default;
+
+  // Move assignment.
+  WeakPtr<T>& operator=(WeakPtr<T>&& r) = default;
+
+  void reset() { flag_ = nullptr; }
+
+  // The following methods should only be called on the same thread as the
+  // "originating" |WeakPtrFactory|.
+
+  explicit operator bool() const { return flag_ && flag_->is_valid(); }
+
+  T* get() const { return *this ? ptr_ : nullptr; }
+
+  T& operator*() const {
+    FXL_DCHECK(*this);
+    return *get();
+  }
+
+  T* operator->() const {
+    FXL_DCHECK(*this);
+    return get();
+  }
+
+ private:
+  template <typename U>
+  friend class WeakPtr;
+
+  friend class WeakPtrFactory<T>;
+
+  explicit WeakPtr(T* ptr, fxl::RefPtr<fml::internal::WeakPtrFlag>&& flag)
+      : ptr_(ptr), flag_(std::move(flag)) {}
+
+  T* ptr_;
+  fxl::RefPtr<fml::internal::WeakPtrFlag> flag_;
+
+  // Copy/move construction/assignment supported.
+};
+
+// Class that produces (valid) |WeakPtr<T>|s. Typically, this is used as a
+// member variable of |T| (preferably the last one -- see below), and |T|'s
+// methods control how weak pointers to it are vended. This class is not
+// thread-safe, and should only be created, destroyed and used on a single
+// thread.
+//
+// Example:
+//
+//  class Controller {
+//   public:
+//    Controller() : ..., weak_factory_(this) {}
+//    ...
+//
+//    void SpawnWorker() { Worker::StartNew(weak_factory_.GetWeakPtr()); }
+//    void WorkComplete(const Result& result) { ... }
+//
+//   private:
+//    ...
+//
+//    // Member variables should appear before the |WeakPtrFactory|, to ensure
+//    // that any |WeakPtr|s to |Controller| are invalidated before its member
+//    // variables' destructors are executed.
+//    WeakPtrFactory<Controller> weak_factory_;
+//  };
+//
+//  class Worker {
+//   public:
+//    static void StartNew(const WeakPtr<Controller>& controller) {
+//      Worker* worker = new Worker(controller);
+//      // Kick off asynchronous processing....
+//    }
+//
+//   private:
+//    Worker(const WeakPtr<Controller>& controller) : controller_(controller) {}
+//
+//    void DidCompleteAsynchronousProcessing(const Result& result) {
+//      if (controller_)
+//        controller_->WorkComplete(result);
+//    }
+//
+//    WeakPtr<Controller> controller_;
+//  };
+template <typename T>
+class WeakPtrFactory {
+ public:
+  explicit WeakPtrFactory(T* ptr) : ptr_(ptr) { FXL_DCHECK(ptr_); }
+  ~WeakPtrFactory() { InvalidateWeakPtrs(); }
+
+  // Gets a new weak pointer, which will be valid until either
+  // |InvalidateWeakPtrs()| is called or this object is destroyed.
+  WeakPtr<T> GetWeakPtr() {
+    if (!flag_)
+      flag_ = fxl::MakeRefCounted<fml::internal::WeakPtrFlag>();
+    return WeakPtr<T>(ptr_, flag_.Clone());
+  }
+
+  // Call this method to invalidate all existing weak pointers. (Note that
+  // additional weak pointers can be produced even after this is called.)
+  void InvalidateWeakPtrs() {
+    if (!flag_)
+      return;
+    flag_->Invalidate();
+    flag_ = nullptr;
+  }
+
+  // Call this method to determine if any weak pointers exist. (Note that a
+  // "false" result is definitive, but a "true" result may not be if weak
+  // pointers are held/reset/destroyed/reassigned on other threads.)
+  bool HasWeakPtrs() const { return flag_ && !flag_->HasOneRef(); }
+
+ private:
+  // Note: See weak_ptr_internal.h for an explanation of why we store the
+  // pointer here, instead of in the "flag".
+  T* const ptr_;
+  fxl::RefPtr<fml::internal::WeakPtrFlag> flag_;
+
+  FXL_DISALLOW_COPY_AND_ASSIGN(WeakPtrFactory);
+};
+
+}  // namespace fml
+
+#endif  // FLUTTER_FML_MEMORY_WEAK_PTR_H_
diff --git a/engine/src/flutter/fml/memory/weak_ptr_internal.cc b/engine/src/flutter/fml/memory/weak_ptr_internal.cc
new file mode 100644
index 0000000000..e5379cbd3d
--- /dev/null
+++ b/engine/src/flutter/fml/memory/weak_ptr_internal.cc
@@ -0,0 +1,26 @@
+// Copyright 2016 The Fuchsia Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "flutter/fml/memory/weak_ptr_internal.h"
+
+#include "lib/fxl/logging.h"
+
+namespace fml {
+namespace internal {
+
+WeakPtrFlag::WeakPtrFlag() : is_valid_(true) {}
+
+WeakPtrFlag::~WeakPtrFlag() {
+  // Should be invalidated before destruction.
+  FXL_DCHECK(!is_valid_);
+}
+
+void WeakPtrFlag::Invalidate() {
+  // Invalidation should happen exactly once.
+  FXL_DCHECK(is_valid_);
+  is_valid_ = false;
+}
+
+}  // namespace internal
+}  // namespace fml
diff --git a/engine/src/flutter/fml/memory/weak_ptr_internal.h b/engine/src/flutter/fml/memory/weak_ptr_internal.h
new file mode 100644
index 0000000000..570bd90ddf
--- /dev/null
+++ b/engine/src/flutter/fml/memory/weak_ptr_internal.h
@@ -0,0 +1,41 @@
+// Copyright 2016 The Fuchsia Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef FLUTTER_FML_MEMORY_WEAK_PTR_INTERNAL_H_
+#define FLUTTER_FML_MEMORY_WEAK_PTR_INTERNAL_H_
+
+#include "lib/fxl/macros.h"
+#include "lib/fxl/memory/ref_counted.h"
+
+namespace fml {
+namespace internal {
+
+// |WeakPtr<T>|s have a reference to a |WeakPtrFlag| to determine whether they
+// are valid (non-null) or not. We do not store a |T*| in this object since
+// there may also be |WeakPtr<U>|s to the same object, where |U| is a superclass
+// of |T|.
+//
+// This class in not thread-safe, though references may be released on any
+// thread (allowing weak pointers to be destroyed/reset/reassigned on any
+// thread).
+class FXL_EXPORT WeakPtrFlag : public fxl::RefCountedThreadSafe<WeakPtrFlag> {
+ public:
+  WeakPtrFlag();
+
+  ~WeakPtrFlag();
+
+  bool is_valid() const { return is_valid_; }
+
+  void Invalidate();
+
+ private:
+  bool is_valid_;
+
+  FXL_DISALLOW_COPY_AND_ASSIGN(WeakPtrFlag);
+};
+
+}  // namespace internal
+}  // namespace fml
+
+#endif  // FLUTTER_FML_MEMORY_WEAK_PTR_INTERNAL_H_
diff --git a/engine/src/flutter/fml/memory/weak_ptr_unittest.cc b/engine/src/flutter/fml/memory/weak_ptr_unittest.cc
new file mode 100644
index 0000000000..2b6dbd035e
--- /dev/null
+++ b/engine/src/flutter/fml/memory/weak_ptr_unittest.cc
@@ -0,0 +1,197 @@
+// Copyright 2016 The Fuchsia Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "flutter/fml/memory/weak_ptr.h"
+
+#include <utility>
+
+#include "gtest/gtest.h"
+
+namespace fml {
+namespace {
+
+TEST(WeakPtrTest, Basic) {
+  int data = 0;
+  WeakPtrFactory<int> factory(&data);
+  WeakPtr<int> ptr = factory.GetWeakPtr();
+  EXPECT_EQ(&data, ptr.get());
+}
+
+TEST(WeakPtrTest, CopyConstruction) {
+  int data = 0;
+  WeakPtrFactory<int> factory(&data);
+  WeakPtr<int> ptr = factory.GetWeakPtr();
+  WeakPtr<int> ptr2(ptr);
+  EXPECT_EQ(&data, ptr.get());
+  EXPECT_EQ(&data, ptr2.get());
+}
+
+TEST(WeakPtrTest, MoveConstruction) {
+  int data = 0;
+  WeakPtrFactory<int> factory(&data);
+  WeakPtr<int> ptr = factory.GetWeakPtr();
+  WeakPtr<int> ptr2(std::move(ptr));
+  EXPECT_EQ(nullptr, ptr.get());
+  EXPECT_EQ(&data, ptr2.get());
+}
+
+TEST(WeakPtrTest, CopyAssignment) {
+  int data = 0;
+  WeakPtrFactory<int> factory(&data);
+  WeakPtr<int> ptr = factory.GetWeakPtr();
+  WeakPtr<int> ptr2;
+  EXPECT_EQ(nullptr, ptr2.get());
+  ptr2 = ptr;
+  EXPECT_EQ(&data, ptr.get());
+  EXPECT_EQ(&data, ptr2.get());
+}
+
+TEST(WeakPtrTest, MoveAssignment) {
+  int data = 0;
+  WeakPtrFactory<int> factory(&data);
+  WeakPtr<int> ptr = factory.GetWeakPtr();
+  WeakPtr<int> ptr2;
+  EXPECT_EQ(nullptr, ptr2.get());
+  ptr2 = std::move(ptr);
+  EXPECT_EQ(nullptr, ptr.get());
+  EXPECT_EQ(&data, ptr2.get());
+}
+
+TEST(WeakPtrTest, Testable) {
+  int data = 0;
+  WeakPtrFactory<int> factory(&data);
+  WeakPtr<int> ptr;
+  EXPECT_EQ(nullptr, ptr.get());
+  EXPECT_FALSE(ptr);
+  ptr = factory.GetWeakPtr();
+  EXPECT_EQ(&data, ptr.get());
+  EXPECT_TRUE(ptr);
+}
+
+TEST(WeakPtrTest, OutOfScope) {
+  WeakPtr<int> ptr;
+  EXPECT_EQ(nullptr, ptr.get());
+  {
+    int data = 0;
+    WeakPtrFactory<int> factory(&data);
+    ptr = factory.GetWeakPtr();
+  }
+  EXPECT_EQ(nullptr, ptr.get());
+}
+
+TEST(WeakPtrTest, Multiple) {
+  WeakPtr<int> a;
+  WeakPtr<int> b;
+  {
+    int data = 0;
+    WeakPtrFactory<int> factory(&data);
+    a = factory.GetWeakPtr();
+    b = factory.GetWeakPtr();
+    EXPECT_EQ(&data, a.get());
+    EXPECT_EQ(&data, b.get());
+  }
+  EXPECT_EQ(nullptr, a.get());
+  EXPECT_EQ(nullptr, b.get());
+}
+
+TEST(WeakPtrTest, MultipleStaged) {
+  WeakPtr<int> a;
+  {
+    int data = 0;
+    WeakPtrFactory<int> factory(&data);
+    a = factory.GetWeakPtr();
+    { WeakPtr<int> b = factory.GetWeakPtr(); }
+    EXPECT_NE(a.get(), nullptr);
+  }
+  EXPECT_EQ(nullptr, a.get());
+}
+
+struct Base {
+  double member = 0.;
+};
+struct Derived : public Base {};
+
+TEST(WeakPtrTest, Dereference) {
+  Base data;
+  data.member = 123456.;
+  WeakPtrFactory<Base> factory(&data);
+  WeakPtr<Base> ptr = factory.GetWeakPtr();
+  EXPECT_EQ(&data, ptr.get());
+  EXPECT_EQ(data.member, (*ptr).member);
+  EXPECT_EQ(data.member, ptr->member);
+}
+
+TEST(WeakPtrTest, UpcastCopyConstruction) {
+  Derived data;
+  WeakPtrFactory<Derived> factory(&data);
+  WeakPtr<Derived> ptr = factory.GetWeakPtr();
+  WeakPtr<Base> ptr2(ptr);
+  EXPECT_EQ(&data, ptr.get());
+  EXPECT_EQ(&data, ptr2.get());
+}
+
+TEST(WeakPtrTest, UpcastMoveConstruction) {
+  Derived data;
+  WeakPtrFactory<Derived> factory(&data);
+  WeakPtr<Derived> ptr = factory.GetWeakPtr();
+  WeakPtr<Base> ptr2(std::move(ptr));
+  EXPECT_EQ(nullptr, ptr.get());
+  EXPECT_EQ(&data, ptr2.get());
+}
+
+TEST(WeakPtrTest, UpcastCopyAssignment) {
+  Derived data;
+  WeakPtrFactory<Derived> factory(&data);
+  WeakPtr<Derived> ptr = factory.GetWeakPtr();
+  WeakPtr<Base> ptr2;
+  EXPECT_EQ(nullptr, ptr2.get());
+  ptr2 = ptr;
+  EXPECT_EQ(&data, ptr.get());
+  EXPECT_EQ(&data, ptr2.get());
+}
+
+TEST(WeakPtrTest, UpcastMoveAssignment) {
+  Derived data;
+  WeakPtrFactory<Derived> factory(&data);
+  WeakPtr<Derived> ptr = factory.GetWeakPtr();
+  WeakPtr<Base> ptr2;
+  EXPECT_EQ(nullptr, ptr2.get());
+  ptr2 = std::move(ptr);
+  EXPECT_EQ(nullptr, ptr.get());
+  EXPECT_EQ(&data, ptr2.get());
+}
+
+TEST(WeakPtrTest, InvalidateWeakPtrs) {
+  int data = 0;
+  WeakPtrFactory<int> factory(&data);
+  WeakPtr<int> ptr = factory.GetWeakPtr();
+  EXPECT_EQ(&data, ptr.get());
+  EXPECT_TRUE(factory.HasWeakPtrs());
+  factory.InvalidateWeakPtrs();
+  EXPECT_EQ(nullptr, ptr.get());
+  EXPECT_FALSE(factory.HasWeakPtrs());
+
+  // Test that the factory can create new weak pointers after a
+  // |InvalidateWeakPtrs()| call, and that they remain valid until the next
+  // |InvalidateWeakPtrs()| call.
+  WeakPtr<int> ptr2 = factory.GetWeakPtr();
+  EXPECT_EQ(&data, ptr2.get());
+  EXPECT_TRUE(factory.HasWeakPtrs());
+  factory.InvalidateWeakPtrs();
+  EXPECT_EQ(nullptr, ptr2.get());
+  EXPECT_FALSE(factory.HasWeakPtrs());
+}
+
+TEST(WeakPtrTest, HasWeakPtrs) {
+  int data = 0;
+  WeakPtrFactory<int> factory(&data);
+  {
+    WeakPtr<int> ptr = factory.GetWeakPtr();
+    EXPECT_TRUE(factory.HasWeakPtrs());
+  }
+  EXPECT_FALSE(factory.HasWeakPtrs());
+}
+
+}  // namespace
+}  // namespace fml
diff --git a/engine/src/flutter/shell/common/animator.cc b/engine/src/flutter/shell/common/animator.cc
index 2602ae7b84..ce6988f65d 100644
--- a/engine/src/flutter/shell/common/animator.cc
+++ b/engine/src/flutter/shell/common/animator.cc
@@ -11,7 +11,7 @@
 
 namespace shell {
 
-Animator::Animator(fxl::WeakPtr<Rasterizer> rasterizer,
+Animator::Animator(fml::WeakPtr<Rasterizer> rasterizer,
                    VsyncWaiter* waiter,
                    Engine* engine)
     : rasterizer_(rasterizer),
diff --git a/engine/src/flutter/shell/common/animator.h b/engine/src/flutter/shell/common/animator.h
index 42d53299e2..7074864d64 100644
--- a/engine/src/flutter/shell/common/animator.h
+++ b/engine/src/flutter/shell/common/animator.h
@@ -18,13 +18,13 @@ namespace shell {
 
 class Animator {
  public:
-  Animator(fxl::WeakPtr<Rasterizer> rasterizer,
+  Animator(fml::WeakPtr<Rasterizer> rasterizer,
            VsyncWaiter* waiter,
            Engine* engine);
 
   ~Animator();
 
-  void set_rasterizer(fxl::WeakPtr<Rasterizer> rasterizer) {
+  void set_rasterizer(fml::WeakPtr<Rasterizer> rasterizer) {
     rasterizer_ = rasterizer;
   }
 
@@ -46,7 +46,7 @@ class Animator {
 
   const char* FrameParity();
 
-  fxl::WeakPtr<Rasterizer> rasterizer_;
+  fml::WeakPtr<Rasterizer> rasterizer_;
   VsyncWaiter* waiter_;
   Engine* engine_;
 
@@ -59,7 +59,7 @@ class Animator {
   bool paused_;
   bool frame_scheduled_;
 
-  fxl::WeakPtrFactory<Animator> weak_factory_;
+  fml::WeakPtrFactory<Animator> weak_factory_;
 
   FXL_DISALLOW_COPY_AND_ASSIGN(Animator);
 };
diff --git a/engine/src/flutter/shell/common/engine.cc b/engine/src/flutter/shell/common/engine.cc
index ee3941ba22..91a9009729 100644
--- a/engine/src/flutter/shell/common/engine.cc
+++ b/engine/src/flutter/shell/common/engine.cc
@@ -82,11 +82,11 @@ Engine::Engine(PlatformView* platform_view)
 
 Engine::~Engine() {}
 
-void Engine::set_rasterizer(fxl::WeakPtr<Rasterizer> rasterizer) {
+void Engine::set_rasterizer(fml::WeakPtr<Rasterizer> rasterizer) {
   animator_->set_rasterizer(rasterizer);
 }
 
-fxl::WeakPtr<Engine> Engine::GetWeakPtr() {
+fml::WeakPtr<Engine> Engine::GetWeakPtr() {
   return weak_factory_.GetWeakPtr();
 }
 
diff --git a/engine/src/flutter/shell/common/engine.h b/engine/src/flutter/shell/common/engine.h
index 5ce57e8f37..8568a22a47 100644
--- a/engine/src/flutter/shell/common/engine.h
+++ b/engine/src/flutter/shell/common/engine.h
@@ -31,7 +31,7 @@ class Engine : public blink::RuntimeDelegate {
 
   ~Engine() override;
 
-  fxl::WeakPtr<Engine> GetWeakPtr();
+  fml::WeakPtr<Engine> GetWeakPtr();
 
   static void Init(const std::string& bundle_path);
 
@@ -75,7 +75,7 @@ class Engine : public blink::RuntimeDelegate {
   void DispatchSemanticsAction(int id, blink::SemanticsAction action);
   void SetSemanticsEnabled(bool enabled);
 
-  void set_rasterizer(fxl::WeakPtr<Rasterizer> rasterizer);
+  void set_rasterizer(fml::WeakPtr<Rasterizer> rasterizer);
 
  private:
   // RuntimeDelegate methods:
@@ -122,7 +122,7 @@ class Engine : public blink::RuntimeDelegate {
   // TODO(eseidel): This should move into an AnimatorStateMachine.
   bool activity_running_;
   bool have_surface_;
-  fxl::WeakPtrFactory<Engine> weak_factory_;
+  fml::WeakPtrFactory<Engine> weak_factory_;
 
   FXL_DISALLOW_COPY_AND_ASSIGN(Engine);
 };
diff --git a/engine/src/flutter/shell/common/null_rasterizer.cc b/engine/src/flutter/shell/common/null_rasterizer.cc
index 80c60638fc..f774208ff2 100644
--- a/engine/src/flutter/shell/common/null_rasterizer.cc
+++ b/engine/src/flutter/shell/common/null_rasterizer.cc
@@ -25,7 +25,7 @@ void NullRasterizer::Teardown(
   teardown_completion_event->Signal();
 }
 
-fxl::WeakPtr<Rasterizer> NullRasterizer::GetWeakRasterizerPtr() {
+fml::WeakPtr<Rasterizer> NullRasterizer::GetWeakRasterizerPtr() {
   return weak_factory_.GetWeakPtr();
 }
 
diff --git a/engine/src/flutter/shell/common/null_rasterizer.h b/engine/src/flutter/shell/common/null_rasterizer.h
index 43e4edb6f2..a5fee836c2 100644
--- a/engine/src/flutter/shell/common/null_rasterizer.h
+++ b/engine/src/flutter/shell/common/null_rasterizer.h
@@ -24,7 +24,7 @@ class NullRasterizer : public Rasterizer {
 
   void Clear(SkColor color, const SkISize& size) override;
 
-  fxl::WeakPtr<Rasterizer> GetWeakRasterizerPtr() override;
+  fml::WeakPtr<Rasterizer> GetWeakRasterizerPtr() override;
 
   flow::LayerTree* GetLastLayerTree() override;
 
@@ -34,7 +34,7 @@ class NullRasterizer : public Rasterizer {
 
  private:
   std::unique_ptr<Surface> surface_;
-  fxl::WeakPtrFactory<NullRasterizer> weak_factory_;
+  fml::WeakPtrFactory<NullRasterizer> weak_factory_;
 
   FXL_DISALLOW_COPY_AND_ASSIGN(NullRasterizer);
 };
diff --git a/engine/src/flutter/shell/common/platform_view_service_protocol.cc b/engine/src/flutter/shell/common/platform_view_service_protocol.cc
index 8a076bbf3f..9f04656573 100644
--- a/engine/src/flutter/shell/common/platform_view_service_protocol.cc
+++ b/engine/src/flutter/shell/common/platform_view_service_protocol.cc
@@ -250,8 +250,8 @@ static sk_sp<SkData> EncodeBitmapAsPNG(const SkBitmap& bitmap) {
   return data;
 }
 
-static fxl::WeakPtr<Rasterizer> GetRandomRasterizer() {
-  fxl::WeakPtr<Rasterizer> rasterizer;
+static fml::WeakPtr<Rasterizer> GetRandomRasterizer() {
+  fml::WeakPtr<Rasterizer> rasterizer;
   Shell::Shared().IteratePlatformViews(
       [&rasterizer](PlatformView* view) -> bool {
         rasterizer = view->rasterizer().GetWeakRasterizerPtr();
diff --git a/engine/src/flutter/shell/common/rasterizer.h b/engine/src/flutter/shell/common/rasterizer.h
index 6739df7098..0a58871046 100644
--- a/engine/src/flutter/shell/common/rasterizer.h
+++ b/engine/src/flutter/shell/common/rasterizer.h
@@ -8,10 +8,10 @@
 #include <memory>
 
 #include "flutter/flow/layers/layer_tree.h"
+#include "flutter/fml/memory/weak_ptr.h"
 #include "flutter/shell/common/surface.h"
 #include "flutter/synchronization/pipeline.h"
 #include "lib/fxl/functional/closure.h"
-#include "lib/fxl/memory/weak_ptr.h"
 #include "lib/fxl/synchronization/waitable_event.h"
 
 namespace shell {
@@ -29,7 +29,7 @@ class Rasterizer {
 
   virtual void Clear(SkColor color, const SkISize& size) = 0;
 
-  virtual fxl::WeakPtr<Rasterizer> GetWeakRasterizerPtr() = 0;
+  virtual fml::WeakPtr<Rasterizer> GetWeakRasterizerPtr() = 0;
 
   virtual flow::LayerTree* GetLastLayerTree() = 0;
 
diff --git a/engine/src/flutter/shell/common/vsync_waiter_fallback.h b/engine/src/flutter/shell/common/vsync_waiter_fallback.h
index 345c328553..bfb7e118b1 100644
--- a/engine/src/flutter/shell/common/vsync_waiter_fallback.h
+++ b/engine/src/flutter/shell/common/vsync_waiter_fallback.h
@@ -5,9 +5,9 @@
 #ifndef FLUTTER_SHELL_COMMON_VSYNC_WAITER_FALLBACK_H_
 #define FLUTTER_SHELL_COMMON_VSYNC_WAITER_FALLBACK_H_
 
+#include "flutter/fml/memory/weak_ptr.h"
 #include "flutter/shell/common/vsync_waiter.h"
 #include "lib/fxl/macros.h"
-#include "lib/fxl/memory/weak_ptr.h"
 #include "lib/fxl/time/time_point.h"
 
 namespace shell {
@@ -23,7 +23,7 @@ class VsyncWaiterFallback : public VsyncWaiter {
   fxl::TimePoint phase_;
   Callback callback_;
 
-  fxl::WeakPtrFactory<VsyncWaiterFallback> weak_factory_;
+  fml::WeakPtrFactory<VsyncWaiterFallback> weak_factory_;
 
   FXL_DISALLOW_COPY_AND_ASSIGN(VsyncWaiterFallback);
 };
diff --git a/engine/src/flutter/shell/gpu/BUILD.gn b/engine/src/flutter/shell/gpu/BUILD.gn
index 6cb36faac8..4547965e18 100644
--- a/engine/src/flutter/shell/gpu/BUILD.gn
+++ b/engine/src/flutter/shell/gpu/BUILD.gn
@@ -27,14 +27,13 @@ source_set("gpu") {
     "$flutter_root/glue",
     "$flutter_root/shell/common",
     "$flutter_root/synchronization",
+    "//flutter/fml",
     "//garnet/public/lib/fxl",
     "//third_party/skia",
     "//third_party/skia:gpu",
   ]
 
-  public_configs = [
-    "$flutter_root:config",
-  ]
+  public_configs = [ "$flutter_root:config" ]
 
   if (shell_enable_vulkan) {
     deps += [ "$flutter_root/vulkan" ]
diff --git a/engine/src/flutter/shell/gpu/gpu_rasterizer.cc b/engine/src/flutter/shell/gpu/gpu_rasterizer.cc
index 49083c1ff0..4abe1e63f7 100644
--- a/engine/src/flutter/shell/gpu/gpu_rasterizer.cc
+++ b/engine/src/flutter/shell/gpu/gpu_rasterizer.cc
@@ -21,7 +21,7 @@ GPURasterizer::GPURasterizer(std::unique_ptr<flow::ProcessInfo> info)
 
 GPURasterizer::~GPURasterizer() = default;
 
-fxl::WeakPtr<Rasterizer> GPURasterizer::GetWeakRasterizerPtr() {
+fml::WeakPtr<Rasterizer> GPURasterizer::GetWeakRasterizerPtr() {
   return weak_factory_.GetWeakPtr();
 }
 
diff --git a/engine/src/flutter/shell/gpu/gpu_rasterizer.h b/engine/src/flutter/shell/gpu/gpu_rasterizer.h
index 61942e003c..b2a3e43ca3 100644
--- a/engine/src/flutter/shell/gpu/gpu_rasterizer.h
+++ b/engine/src/flutter/shell/gpu/gpu_rasterizer.h
@@ -29,7 +29,7 @@ class GPURasterizer : public Rasterizer {
   void Teardown(
       fxl::AutoResetWaitableEvent* teardown_completion_event) override;
 
-  fxl::WeakPtr<Rasterizer> GetWeakRasterizerPtr() override;
+  fml::WeakPtr<Rasterizer> GetWeakRasterizerPtr() override;
 
   flow::LayerTree* GetLastLayerTree() override;
 
@@ -46,7 +46,7 @@ class GPURasterizer : public Rasterizer {
   // next time. NULL if there is no callback or the callback was set back to
   // NULL after being called.
   fxl::Closure nextFrameCallback_;
-  fxl::WeakPtrFactory<GPURasterizer> weak_factory_;
+  fml::WeakPtrFactory<GPURasterizer> weak_factory_;
 
   void DoDraw(std::unique_ptr<flow::LayerTree> layer_tree);
 
diff --git a/engine/src/flutter/shell/gpu/gpu_surface_gl.h b/engine/src/flutter/shell/gpu/gpu_surface_gl.h
index d3b6a9bf5f..3938a0845a 100644
--- a/engine/src/flutter/shell/gpu/gpu_surface_gl.h
+++ b/engine/src/flutter/shell/gpu/gpu_surface_gl.h
@@ -5,10 +5,10 @@
 #ifndef SHELL_GPU_GPU_SURFACE_GL_H_
 #define SHELL_GPU_GPU_SURFACE_GL_H_
 
+#include "flutter/fml/memory/weak_ptr.h"
 #include "flutter/shell/common/surface.h"
 #include "flutter/synchronization/debug_thread_checker.h"
 #include "lib/fxl/macros.h"
-#include "lib/fxl/memory/weak_ptr.h"
 #include "third_party/skia/include/gpu/GrContext.h"
 
 namespace shell {
@@ -44,7 +44,7 @@ class GPUSurfaceGL : public Surface {
   sk_sp<SkSurface> onscreen_surface_;
   sk_sp<SkSurface> offscreen_surface_;
   bool valid_ = false;
-  fxl::WeakPtrFactory<GPUSurfaceGL> weak_factory_;
+  fml::WeakPtrFactory<GPUSurfaceGL> weak_factory_;
 
   bool CreateOrUpdateSurfaces(const SkISize& size);
 
diff --git a/engine/src/flutter/shell/gpu/gpu_surface_software.h b/engine/src/flutter/shell/gpu/gpu_surface_software.h
index 557742558e..f7312153db 100644
--- a/engine/src/flutter/shell/gpu/gpu_surface_software.h
+++ b/engine/src/flutter/shell/gpu/gpu_surface_software.h
@@ -5,9 +5,9 @@
 #ifndef FLUTTER_SHELL_GPU_GPU_SURFACE_SOFTWARE_H_
 #define FLUTTER_SHELL_GPU_GPU_SURFACE_SOFTWARE_H_
 
+#include "flutter/fml/memory/weak_ptr.h"
 #include "flutter/shell/common/surface.h"
 #include "lib/fxl/macros.h"
-#include "lib/fxl/memory/weak_ptr.h"
 #include "third_party/skia/include/core/SkSurface.h"
 
 namespace shell {
@@ -35,7 +35,7 @@ class GPUSurfaceSoftware : public Surface {
  private:
   GPUSurfaceSoftwareDelegate* delegate_;
 
-  fxl::WeakPtrFactory<GPUSurfaceSoftware> weak_factory_;
+  fml::WeakPtrFactory<GPUSurfaceSoftware> weak_factory_;
 
   FXL_DISALLOW_COPY_AND_ASSIGN(GPUSurfaceSoftware);
 };
diff --git a/engine/src/flutter/shell/gpu/gpu_surface_vulkan.h b/engine/src/flutter/shell/gpu/gpu_surface_vulkan.h
index d88dbdee34..eafed43a62 100644
--- a/engine/src/flutter/shell/gpu/gpu_surface_vulkan.h
+++ b/engine/src/flutter/shell/gpu/gpu_surface_vulkan.h
@@ -6,11 +6,11 @@
 #define SHELL_GPU_GPU_SURFACE_VULKAN_H_
 
 #include <memory>
+#include "flutter/fml/memory/weak_ptr.h"
 #include "flutter/shell/common/surface.h"
 #include "flutter/vulkan/vulkan_native_surface.h"
 #include "flutter/vulkan/vulkan_window.h"
 #include "lib/fxl/macros.h"
-#include "lib/fxl/memory/weak_ptr.h"
 
 namespace shell {
 
@@ -29,7 +29,7 @@ class GPUSurfaceVulkan : public Surface {
 
  private:
   vulkan::VulkanWindow window_;
-  fxl::WeakPtrFactory<GPUSurfaceVulkan> weak_factory_;
+  fml::WeakPtrFactory<GPUSurfaceVulkan> weak_factory_;
 
   FXL_DISALLOW_COPY_AND_ASSIGN(GPUSurfaceVulkan);
 };
diff --git a/engine/src/flutter/shell/platform/android/vsync_waiter_android.cc b/engine/src/flutter/shell/platform/android/vsync_waiter_android.cc
index 2b316cd556..29e1958dcc 100644
--- a/engine/src/flutter/shell/platform/android/vsync_waiter_android.cc
+++ b/engine/src/flutter/shell/platform/android/vsync_waiter_android.cc
@@ -26,8 +26,8 @@ VsyncWaiterAndroid::~VsyncWaiterAndroid() = default;
 void VsyncWaiterAndroid::AsyncWaitForVsync(Callback callback) {
   FXL_DCHECK(!callback_);
   callback_ = std::move(callback);
-  fxl::WeakPtr<VsyncWaiterAndroid>* weak =
-      new fxl::WeakPtr<VsyncWaiterAndroid>();
+  fml::WeakPtr<VsyncWaiterAndroid>* weak =
+      new fml::WeakPtr<VsyncWaiterAndroid>();
   *weak = weak_factory_.GetWeakPtr();
 
   blink::Threads::Platform()->PostTask([weak] {
@@ -70,8 +70,8 @@ static void OnNativeVsync(JNIEnv* env,
     TRACE_EVENT2("flutter", "VSYNC", "mode", "basic", "deadline", deadline);
   }
 #endif
-  fxl::WeakPtr<VsyncWaiterAndroid>* weak =
-      reinterpret_cast<fxl::WeakPtr<VsyncWaiterAndroid>*>(cookie);
+  fml::WeakPtr<VsyncWaiterAndroid>* weak =
+      reinterpret_cast<fml::WeakPtr<VsyncWaiterAndroid>*>(cookie);
   VsyncWaiterAndroid* waiter = weak->get();
   delete weak;
   if (waiter) {
diff --git a/engine/src/flutter/shell/platform/android/vsync_waiter_android.h b/engine/src/flutter/shell/platform/android/vsync_waiter_android.h
index 8b272c6b18..c73af4bfca 100644
--- a/engine/src/flutter/shell/platform/android/vsync_waiter_android.h
+++ b/engine/src/flutter/shell/platform/android/vsync_waiter_android.h
@@ -6,9 +6,9 @@
 #define SHELL_PLATFORM_ANDROID_VSYNC_WAITER_ANDROID_H_
 
 #include <jni.h>
+#include "flutter/fml/memory/weak_ptr.h"
 #include "flutter/shell/common/vsync_waiter.h"
 #include "lib/fxl/macros.h"
-#include "lib/fxl/memory/weak_ptr.h"
 
 namespace shell {
 
@@ -26,9 +26,8 @@ class VsyncWaiterAndroid : public VsyncWaiter {
 
  private:
   Callback callback_;
-  fxl::WeakPtr<VsyncWaiterAndroid> self_;
-
-  fxl::WeakPtrFactory<VsyncWaiterAndroid> weak_factory_;
+  fml::WeakPtr<VsyncWaiterAndroid> self_;
+  fml::WeakPtrFactory<VsyncWaiterAndroid> weak_factory_;
 
   FXL_DISALLOW_COPY_AND_ASSIGN(VsyncWaiterAndroid);
 };
diff --git a/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterView.mm b/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterView.mm
index db6812f5f0..7c382838c6 100644
--- a/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterView.mm
+++ b/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterView.mm
@@ -44,7 +44,7 @@
   return YES;
 }
 
-void SnapshotRasterizer(fxl::WeakPtr<shell::Rasterizer> rasterizer,
+void SnapshotRasterizer(fml::WeakPtr<shell::Rasterizer> rasterizer,
                         CGContextRef context,
                         bool is_opaque) {
   if (!rasterizer) {
@@ -89,8 +89,8 @@ void SnapshotRasterizer(fxl::WeakPtr<shell::Rasterizer> rasterizer,
   SkCGDrawBitmap(context, bitmap, 0, 0);
 }
 
-static fxl::WeakPtr<shell::Rasterizer> GetRandomRasterizer() {
-  fxl::WeakPtr<shell::Rasterizer> rasterizer;
+static fml::WeakPtr<shell::Rasterizer> GetRandomRasterizer() {
+  fml::WeakPtr<shell::Rasterizer> rasterizer;
   shell::Shell::Shared().IteratePlatformViews([&rasterizer](shell::PlatformView* view) -> bool {
     rasterizer = view->rasterizer().GetWeakRasterizerPtr();
     // We just grab the first rasterizer so there is no need to iterate
diff --git a/engine/src/flutter/shell/platform/darwin/ios/platform_view_ios.h b/engine/src/flutter/shell/platform/darwin/ios/platform_view_ios.h
index 0b4bc9d9ec..f9c6cafacc 100644
--- a/engine/src/flutter/shell/platform/darwin/ios/platform_view_ios.h
+++ b/engine/src/flutter/shell/platform/darwin/ios/platform_view_ios.h
@@ -7,13 +7,13 @@
 
 #include <memory>
 
+#include "flutter/fml/memory/weak_ptr.h"
 #include "flutter/shell/common/platform_view.h"
 #include "flutter/shell/platform/darwin/ios/framework/Source/accessibility_bridge.h"
 #include "flutter/shell/platform/darwin/ios/framework/Source/platform_message_router.h"
 #include "flutter/shell/platform/darwin/ios/ios_surface.h"
 #include "lib/fxl/functional/closure.h"
 #include "lib/fxl/macros.h"
-#include "lib/fxl/memory/weak_ptr.h"
 
 @class CALayer;
 @class UIView;
@@ -39,7 +39,7 @@ class PlatformViewIOS : public PlatformView {
     return platform_message_router_;
   }
 
-  fxl::WeakPtr<PlatformViewIOS> GetWeakPtr();
+  fml::WeakPtr<PlatformViewIOS> GetWeakPtr();
 
   void UpdateSurfaceSize();
 
@@ -65,7 +65,7 @@ class PlatformViewIOS : public PlatformView {
   PlatformMessageRouter platform_message_router_;
   std::unique_ptr<AccessibilityBridge> accessibility_bridge_;
   fxl::Closure firstFrameCallback_;
-  fxl::WeakPtrFactory<PlatformViewIOS> weak_factory_;
+  fml::WeakPtrFactory<PlatformViewIOS> weak_factory_;
   NSObject<FlutterBinaryMessenger>* binary_messenger_;
 
   void SetupAndLoadFromSource(const std::string& assets_directory,
diff --git a/engine/src/flutter/shell/platform/darwin/ios/platform_view_ios.mm b/engine/src/flutter/shell/platform/darwin/ios/platform_view_ios.mm
index ba0e87577f..fa1871816c 100644
--- a/engine/src/flutter/shell/platform/darwin/ios/platform_view_ios.mm
+++ b/engine/src/flutter/shell/platform/darwin/ios/platform_view_ios.mm
@@ -68,7 +68,7 @@ void PlatformViewIOS::SetupAndLoadFromSource(const std::string& assets_directory
       });
 }
 
-fxl::WeakPtr<PlatformViewIOS> PlatformViewIOS::GetWeakPtr() {
+fml::WeakPtr<PlatformViewIOS> PlatformViewIOS::GetWeakPtr() {
   return weak_factory_.GetWeakPtr();
 }