fix and re-enable SessionConnection unit tests (flutter/engine#19812)

[fuchsia] fix and re-enable SessionConnection unittests

This change waits until Scenic is initialized before beginning the test
logic. This should fix the issue where the test starts running before or
during Scenic startup.

engine/src/flutter/shell/platform/fuchsia/flutter/meta/flutter_runner_scenic_tests.cmx

@@ -14,6 +14,7 @@
       "fuchsia.sys.Environment",
       "fuchsia.sysmem.Allocator",
       "fuchsia.tracing.provider.Registry",
+      "fuchsia.ui.input.ImeService",
       "fuchsia.ui.policy.Presenter",
       "fuchsia.ui.scenic.Scenic",
       "fuchsia.vulkan.loader.Loader"

engine/src/flutter/shell/platform/fuchsia/flutter/tests/session_connection_unittests.cc

@@ -34,9 +34,21 @@ class SessionConnectionTest : public ::testing::Test {
     view_token_ = std::move(view_token);
 
     scenic_->CreateSession(session_.NewRequest(), session_listener_.Bind());
-    presenter_->PresentView(std::move(view_holder_token), nullptr);
+    presenter_->PresentOrReplaceView(std::move(view_holder_token), nullptr);
 
     FML_CHECK(zx::event::create(0, &vsync_event_) == ZX_OK);
+
+    // Ensure Scenic has had time to wake up before the test logic begins.
+    // TODO(61768) Find a better solution than sleeping periodically checking a
+    // condition.
+    int scenic_initialized = false;
+    scenic_->GetDisplayInfo(
+        [&scenic_initialized](fuchsia::ui::gfx::DisplayInfo display_info) {
+          scenic_initialized = true;
+        });
+    while (!scenic_initialized) {
+      std::this_thread::sleep_for(std::chrono::milliseconds(100));
+    }
   }
   // Warning: Initialization order matters here. |loop_| must be initialized
   // before |SetUp()| so that we have a dispatcher already initialized.

engine/src/flutter/testing/fuchsia/run_tests.sh

@@ -198,7 +198,6 @@ echo "$(date) START:flutter_runner_tests ----------------------------"
     -f flutter_aot_runner-0.far    \
     -f flutter_runner_scenic_tests-0.far  \
     -t flutter_runner_scenic_tests \
-    -a "--gtest_filter=-SessionConnectionTest.*:CalculateNextLatchPointTest.*" \
     --identity-file $pkey \
     --timeout-seconds $test_timeout_seconds \
     --packages-directory packages