Rationalize embedder.dart and shell.dart

This patch combines embedder.dart and shell.dart into one thing. We should now
handle a bunch of error cases better.

  * embedder.connectToApplication has moved to shell.connectToApplication,
    matching the rest of the mojo universe.
  * embedder.connecttoService has moved to shell.connnectToService (and merged
    with shell.requestService).
  * shell.requestService is now shell.connectToService, matching the rest of
    the mojo universe.
  * serviceRegistry has moved from embedder.serviceRegistry to a top-level
    getter.

Fixes #1803

examples/widgets/piano.dart

@@ -68,7 +68,7 @@ class PianoApp extends StatelessComponent {
   Future _loadSounds() async {
     MediaServiceProxy mediaService = new MediaServiceProxy.unbound();
     try {
-      shell.requestService(null, mediaService);
+      shell.connectToService(null, mediaService);
       List<Future<MediaPlayerPrepareResponseParams>> pending = <Future<MediaPlayerPrepareResponseParams>>[];
       for (PianoKey key in keys)
         pending.add(key.load(mediaService));

packages/flutter/lib/services.dart

@@ -13,7 +13,6 @@ library services;
 
 export 'src/services/activity.dart';
 export 'src/services/asset_bundle.dart';
-export 'src/services/embedder.dart';
 export 'src/services/fetch.dart';
 export 'src/services/image_cache.dart';
 export 'src/services/image_decoder.dart';

packages/flutter/lib/src/services/activity.dart

@@ -22,7 +22,7 @@ const int MULTIPLE_TASK = 0x08000000;
 
 ActivityProxy _initActivityProxy() {
   ActivityProxy activity = new ActivityProxy.unbound();
-  shell.requestService('mojo:sky_viewer', activity);
+  shell.connectToService(null, activity);
   return activity;
 }
 
@@ -40,7 +40,7 @@ final UserFeedback userFeedback = _userFeedbackProxy.ptr;
 
 PathServiceProxy _initPathServiceProxy() {
   PathServiceProxy proxy = new PathServiceProxy.unbound();
-  shell.requestService(null, proxy);
+  shell.connectToService(null, proxy);
   return proxy;
 }
 

packages/flutter/lib/src/services/asset_bundle.dart

@@ -44,7 +44,7 @@ class NetworkAssetBundle extends AssetBundle {
 Future _fetchAndUnpackBundle(String relativeUrl, AssetBundleProxy bundle) async {
   core.MojoDataPipeConsumer bundleData = (await fetchUrl(relativeUrl)).body;
   AssetUnpackerProxy unpacker = new AssetUnpackerProxy.unbound();
-  shell.requestService("mojo:asset_bundle", unpacker);
+  shell.connectToService("mojo:asset_bundle", unpacker);
   unpacker.ptr.unpackZipStream(bundleData, bundle);
   unpacker.close();
 }

packages/flutter/lib/src/services/embedder.dart

@@ -1,72 +0,0 @@
-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-import 'dart:ui_internals' as internals;
-
-import 'package:mojo/application.dart';
-import 'package:mojo/bindings.dart' as bindings;
-import 'package:mojo/core.dart' as core;
-import 'package:mojo/mojo/service_provider.mojom.dart';
-import 'package:mojo/mojo/shell.mojom.dart';
-import 'package:mojo_services/mojo/service_registry.mojom.dart';
-
-final _EmbedderImpl embedder = new _EmbedderImpl();
-
-class _EmbedderImpl {
-  ApplicationConnection _connection;
-  ServiceRegistryProxy _serviceRegistry;
-  ShellProxy _shell;
-  bool _internalsHasNoShell = false;
-
-  ShellProxy get shell {
-    if (_internalsHasNoShell || _shell != null) return _shell;
-
-    try {
-      _shell = new ShellProxy.fromHandle(
-          new core.MojoHandle(internals.takeShellProxyHandle()));
-    } catch (e) {
-      _internalsHasNoShell = true;
-    }
-    return _shell;
-  }
-
-  ApplicationConnection get connection {
-    if (_connection == null) {
-      var stubHandle =
-          new core.MojoHandle(internals.takeServicesProvidedToEmbedder());
-      var proxyHandle =
-          new core.MojoHandle(internals.takeServicesProvidedByEmbedder());
-      _connection = new ApplicationConnection(stubHandle.isValid
-          ? new ServiceProviderStub.fromHandle(stubHandle)
-          : null, proxyHandle.isValid
-          ? new ServiceProviderProxy.fromHandle(proxyHandle)
-          : null);
-    }
-    return _connection;
-  }
-
-  ApplicationConnection connectToApplication(String url) {
-    var proxy = new ServiceProviderProxy.unbound();
-    var stub = new ServiceProviderStub.unbound();
-    shell.ptr.connectToApplication(url, proxy, stub);
-    return new ApplicationConnection(stub, proxy);
-  }
-
-  void connectToService(String url, bindings.ProxyBase proxy) {
-    var appSp = new ServiceProviderProxy.unbound();
-    shell.ptr.connectToApplication(url, appSp, null);
-    var pipe = new core.MojoMessagePipe();
-    proxy.impl.bind(pipe.endpoints[0]);
-    appSp.ptr.connectToService(proxy.name, pipe.endpoints[1]);
-    appSp.close();
-  }
-
-  ServiceRegistryProxy get serviceRegistry {
-    if (_serviceRegistry == null) {
-      _serviceRegistry = new ServiceRegistryProxy.fromHandle(
-          new core.MojoHandle(internals.takeServiceRegistry()));
-    }
-    return _serviceRegistry;
-  }
-}

packages/flutter/lib/src/services/fetch.dart

@@ -17,7 +17,7 @@ export 'package:mojo/mojo/url_response.mojom.dart' show UrlResponse;
 
 NetworkServiceProxy _initNetworkService() {
   NetworkServiceProxy networkService = new NetworkServiceProxy.unbound();
-  shell.requestService("mojo:authenticated_network_service", networkService);
+  shell.connectToService("mojo:authenticated_network_service", networkService);
   return networkService;
 }
 

packages/flutter/lib/src/services/keyboard.dart

@@ -14,7 +14,7 @@ class _KeyboardConnection {
 
   _KeyboardConnection() {
     proxy = new KeyboardServiceProxy.unbound();
-    shell.requestService("mojo:keyboard", proxy);
+    shell.connectToService("mojo:keyboard", proxy);
   }
 
   KeyboardServiceProxy proxy;

packages/flutter/lib/src/services/service_registry.dart

@@ -0,0 +1,18 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:ui_internals' as internals;
+
+import 'package:mojo_services/mojo/service_registry.mojom.dart';
+import 'package:mojo/core.dart' as core;
+
+ServiceRegistryProxy _initServiceRegistryProxy() {
+  core.MojoHandle serviceRegistryHandle = new core.MojoHandle(internals.takeShellProxyHandle());
+  if (!serviceRegistryHandle.isValid)
+    return null;
+  return new ServiceRegistryProxy.fromHandle(serviceRegistryHandle);
+}
+
+final ServiceRegistryProxy _serviceRegistryProxy = _initServiceRegistryProxy();
+final ServiceRegistry serviceRegistry = _serviceRegistryProxy?.ptr;

packages/flutter/lib/src/services/shell.dart

@@ -5,47 +5,74 @@
 import 'dart:ui_internals' as internals;
 
 import 'package:mojo/application.dart';
+import 'package:mojo/bindings.dart' as bindings;
 import 'package:mojo/core.dart' as core;
 import 'package:mojo/mojo/service_provider.mojom.dart';
+import 'package:mojo/mojo/shell.mojom.dart';
 
-import 'embedder.dart';
-
-ApplicationConnection _initConnection() {
-  int rawHandle = internals.takeServicesProvidedByEmbedder();
-  core.MojoHandle proxyHandle = new core.MojoHandle(rawHandle);
-  ServiceProviderProxy serviceProvider = null;
-  if (proxyHandle.isValid) serviceProvider =
-      new ServiceProviderProxy.fromHandle(proxyHandle);
-  return new ApplicationConnection(null, serviceProvider);
-}
-
-// A replacement for requestService.  Implementations should return true
+// A replacement for shell.connectToService.  Implementations should return true
 // if they handled the request, or false if the request should fall through
 // to the default requestService.
-typedef bool OverrideRequestService(String url, Object proxy);
+typedef bool OverrideConnectToService(String url, Object proxy);
 
-// Set this to intercept calls to requestService and supply an alternative
-// implementation of a service (for example, a mock for testing).
-OverrideRequestService overrideRequestService;
+// Set this to intercept calls to shell.connectToService and supply an
+// alternative implementation of a service (for example, a mock for testing).
+OverrideConnectToService overrideConnectToService;
 
-class _ShellImpl {
-  _ShellImpl._();
+ShellProxy _initShellProxy() {
+  core.MojoHandle shellHandle = new core.MojoHandle(internals.takeShellProxyHandle());
+  if (!shellHandle.isValid)
+    return null;
+  return new ShellProxy.fromHandle(shellHandle);
+}
 
-  final ApplicationConnection _connection = _initConnection();
+ApplicationConnection _initEmbedderConnection() {
+  core.MojoHandle servicesHandle = new core.MojoHandle(internals.takeServicesProvidedByEmbedder());
+  core.MojoHandle exposedServicesHandle = new core.MojoHandle(internals.takeServicesProvidedToEmbedder());
+  ServiceProviderProxy services = servicesHandle.isValid ?
+      new ServiceProviderProxy.fromHandle(servicesHandle) : null;
+  ServiceProviderStub exposedServices = exposedServicesHandle.isValid ?
+      new ServiceProviderStub.fromHandle(exposedServicesHandle) : null;
+  return new ApplicationConnection(exposedServices, services);
+}
 
-  void _requestService(String url, Object proxy) {
-    if (embedder.shell == null) _connection.requestService(proxy);
-    else embedder.connectToService(url, proxy);
+final ShellProxy _shellProxy = _initShellProxy();
+final Shell _shell = _shellProxy?.ptr;
+final ApplicationConnection _embedderConnection = _initEmbedderConnection();
+
+class _Shell {
+  _Shell._();
+
+  ApplicationConnection connectToApplication(String url) {
+    if (_shell == null)
+      return null;
+    ServiceProviderProxy services = new ServiceProviderProxy.unbound();
+    ServiceProviderStub exposedServices = new ServiceProviderStub.unbound();
+    _shell.connectToApplication(url, services, exposedServices);
+    return new ApplicationConnection(exposedServices, services);
   }
 
-  void requestService(String url, Object proxy) {
-    if (overrideRequestService != null) {
-      if (overrideRequestService(url, proxy))
-        return;
+  void _connectToService(String url, bindings.ProxyBase proxy) {
+    if (_shell == null || url == null) {
+      // If we don't have a shell or a url, we try to get the services from the
+      // embedder directly instead of using the shell to connect.
+      _embedderConnection.requestService(proxy);
+      return;
     }
 
-    _requestService(url, proxy);
+    ServiceProviderProxy services = new ServiceProviderProxy.unbound();
+    _shell.connectToApplication(url, services, null);
+    var pipe = new core.MojoMessagePipe();
+    proxy.impl.bind(pipe.endpoints[0]);
+    services.ptr.connectToService(proxy.name, pipe.endpoints[1]);
+    services.close();
+  }
+
+  void connectToService(String url, Object proxy) {
+    if (overrideConnectToService != null && overrideConnectToService(url, proxy))
+      return;
+    _connectToService(url, proxy);
   }
 }
 
-final _ShellImpl shell = new _ShellImpl._();
+final _Shell shell = new _Shell._();

packages/flutter_sprites/lib/src/sound.dart

@@ -55,7 +55,7 @@ class SoundEffectPlayer {
 
   SoundEffectPlayer() {
     _mediaService = new MediaServiceProxy.unbound();
-    shell.requestService(null, _mediaService);
+    shell.connectToService(null, _mediaService);
   }
 
   MediaServiceProxy _mediaService;
@@ -165,7 +165,7 @@ class SoundTrackPlayer {
 
   SoundTrackPlayer() {
     _mediaService = new MediaServiceProxy.unbound();
-    shell.requestService(null, _mediaService);
+    shell.connectToService(null, _mediaService);
   }
 
   MediaServiceProxy _mediaService;

packages/unit/test/services/mock_services.dart

@@ -4,13 +4,13 @@ import 'package:flutter/src/services/shell.dart' as shell;
 // of Mojo services.
 class _ServiceMocker {
   _ServiceMocker() {
-    shell.overrideRequestService = _requestService;
+    shell.overrideConnectToService = _connectToService;
   }
 
   // Map of interface names to mock implementations.
   Map<String, Object> _interfaceMock = new Map<String, Object>();
 
-  bool _requestService(String url, dynamic proxy) {
+  bool _connectToService(String url, dynamic proxy) {
     Object mock = _interfaceMock[proxy.impl.name];
     if (mock != null) {
       // Replace the proxy's implementation of the service interface with the

packages/updater/lib/main.dart

@@ -23,7 +23,7 @@ const String kBundleFile = 'app.flx';
 
 UpdateServiceProxy _initUpdateService() {
   UpdateServiceProxy updateService = new UpdateServiceProxy.unbound();
-  shell.requestService(null, updateService);
+  shell.connectToService(null, updateService);
   return updateService;
 }