Split services/ into services/ and foundation/ (#3350)

We're getting back to the point where we have a bunch of foundation APIs
and it's getting confusing having them mixed with services/.

packages/flutter/lib/foundation.dart

@@ -0,0 +1,14 @@
+// Copyright 2016 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.
+
+/// Core Flutter framework primitives.
+///
+/// The features defined in this library are the lowest-level utility
+/// classes and functions used by all the other layers of the Flutter
+/// framework.
+library foundation;
+
+export 'src/foundation/assertions.dart';
+export 'src/foundation/binding.dart';
+export 'src/foundation/print.dart';

packages/flutter/lib/rendering.dart

@@ -48,4 +48,5 @@ export 'src/rendering/table.dart';
 export 'src/rendering/view.dart';
 export 'src/rendering/viewport.dart';
 
+export 'package:flutter/foundation.dart';
 export 'package:vector_math/vector_math_64.dart' show Matrix4;

packages/flutter/lib/services.dart

@@ -7,13 +7,13 @@
 /// For example, this library includes [fetch], which fetches data from the
 /// network.
 ///
-/// This library depends only on core Dart libraries as well as the `mojo`,
-/// `mojo_services`, and `sky_services` and packages.
+/// This library depends only on core Dart libraries, the `mojo`,
+/// `mojo_services`, and `sky_services` packages, and the `foundation`
+/// Flutter library.
 library services;
 
 export 'src/services/activity.dart';
 export 'src/services/app_messages.dart';
-export 'src/services/assertions.dart';
 export 'src/services/asset_bundle.dart';
 export 'src/services/binding.dart';
 export 'src/services/fetch.dart';
@@ -21,4 +21,4 @@ export 'src/services/image_cache.dart';
 export 'src/services/image_decoder.dart';
 export 'src/services/image_resource.dart';
 export 'src/services/keyboard.dart';
-export 'src/services/print.dart';
+export 'src/services/shell.dart';

packages/flutter/lib/src/foundation/README.md

@@ -0,0 +1,4 @@
+The rule for packages in this directory is that they can depend on
+nothing but core Dart packages. They can't depend on `dart:ui`, they
+can't depend on any `package:`, and they can't depend on anything
+outside this directory.

packages/flutter/lib/src/foundation/binding.dart

@@ -0,0 +1,45 @@
+// Copyright 2016 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.
+
+/// Base class for mixins that provide singleton services (also known as
+/// "bindings").
+///
+/// To use this class in a mixin, inherit from it and implement
+/// [initInstances()]. The mixin is guaranteed to only be constructed once in
+/// the lifetime of the app (more precisely, it will assert if constructed twice
+/// in checked mode).
+///
+/// The top-most layer used to write the application will have a
+/// concrete class that inherits from BindingBase and uses all the
+/// various BindingBase mixins (such as [Services]). For example, the
+/// Widgets library in flutter introduces a binding called
+/// [WidgetFlutterBinding]. The relevant library defines how to create
+/// the binding. It could be implied (for example,
+/// [WidgetFlutterBinding] is automatically started from [runApp]), or
+/// the application might be required to explicitly call the
+/// constructor.
+abstract class BindingBase {
+  BindingBase() {
+    assert(!_debugInitialized);
+    initInstances();
+    assert(_debugInitialized);
+  }
+
+  static bool _debugInitialized = false;
+
+  /// The initialization method. Subclasses override this method to hook into
+  /// the platform and otherwise configure their services. Subclasses must call
+  /// "super.initInstances()".
+  ///
+  /// By convention, if the service is to be provided as a singleton, it should
+  /// be exposed as `MixinClassName.instance`, a static getter that returns
+  /// `MixinClassName._instance`, a static field that is set by
+  /// `initInstances()`.
+  void initInstances() {
+    assert(() { _debugInitialized = true; return true; });
+  }
+
+  @override
+  String toString() => '<$runtimeType>';
+}

packages/flutter/lib/src/gestures/binding.dart

@@ -5,7 +5,7 @@
 import 'dart:typed_data';
 import 'dart:ui' as ui show window;
 
-import 'package:flutter/services.dart';
+import 'package:flutter/foundation.dart';
 import 'package:mojo/bindings.dart' as mojo_bindings;
 import 'package:mojo/core.dart' as mojo_core;
 import 'package:sky_services/pointer/pointer.mojom.dart';

packages/flutter/lib/src/gestures/pointer_router.dart

@@ -4,7 +4,7 @@
 
 import 'dart:collection';
 
-import 'package:flutter/services.dart';
+import 'package:flutter/foundation.dart';
 
 import 'events.dart';
 

packages/flutter/lib/src/http/mojo_client.dart

@@ -6,13 +6,14 @@ import 'dart:async';
 import 'dart:convert';
 import 'dart:typed_data';
 
+import 'package:flutter/foundation.dart';
 import 'package:flutter/services.dart';
-import 'package:mojo_services/mojo/network_service.mojom.dart' as mojom;
-import 'package:mojo_services/mojo/url_loader.mojom.dart' as mojom;
 import 'package:mojo/core.dart' as mojo;
+import 'package:mojo/mojo/http_header.mojom.dart' as mojom;
 import 'package:mojo/mojo/url_request.mojom.dart' as mojom;
 import 'package:mojo/mojo/url_response.mojom.dart' as mojom;
-import 'package:mojo/mojo/http_header.mojom.dart' as mojom;
+import 'package:mojo_services/mojo/network_service.mojom.dart' as mojom;
+import 'package:mojo_services/mojo/url_loader.mojom.dart' as mojom;
 
 import 'response.dart';
 

packages/flutter/lib/src/painting/text_painter.dart

@@ -5,7 +5,7 @@
 import 'dart:ui' as ui show Paragraph, ParagraphBuilder, ParagraphStyle, TextBox;
 
 import 'package:flutter/gestures.dart';
-import 'package:flutter/services.dart';
+import 'package:flutter/foundation.dart';
 
 import 'basic_types.dart';
 import 'text_editing.dart';

packages/flutter/lib/src/rendering/binding.dart

@@ -4,6 +4,7 @@
 
 import 'dart:ui' as ui show window;
 
+import 'package:flutter/foundation.dart';
 import 'package:flutter/gestures.dart';
 import 'package:flutter/scheduler.dart';
 import 'package:flutter/services.dart';

packages/flutter/lib/src/rendering/object.dart

@@ -5,10 +5,10 @@
 import 'dart:developer';
 import 'dart:ui' as ui show ImageFilter, PictureRecorder;
 
+import 'package:flutter/foundation.dart';
 import 'package:flutter/gestures.dart';
 import 'package:flutter/painting.dart';
 import 'package:flutter/scheduler.dart';
-import 'package:flutter/services.dart';
 import 'package:mojo_services/mojo/gfx/composition/scene_token.mojom.dart' as mojom;
 import 'package:vector_math/vector_math_64.dart';
 
@@ -20,7 +20,7 @@ import 'binding.dart';
 
 export 'package:flutter/gestures.dart' show HitTestEntry, HitTestResult;
 export 'package:flutter/painting.dart';
-export 'package:flutter/services.dart' show FlutterError, InformationCollector;
+export 'package:flutter/foundation.dart' show FlutterError, InformationCollector;
 
 /// Base class for data associated with a [RenderObject] by its parent.
 ///

packages/flutter/lib/src/scheduler/scheduler.dart

@@ -9,7 +9,7 @@ import 'dart:ui' as ui show window;
 import 'dart:ui' show VoidCallback;
 
 import 'package:collection/collection.dart';
-import 'package:flutter/services.dart';
+import 'package:flutter/foundation.dart';
 
 export 'dart:ui' show VoidCallback;
 

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

@@ -7,7 +7,7 @@ import 'dart:async';
 
 import 'package:sky_services/activity/activity.mojom.dart';
 
-import 'binding.dart';
+import 'shell.dart';
 
 export 'package:sky_services/activity/activity.mojom.dart';
 

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

@@ -4,10 +4,11 @@
 
 import 'dart:async';
 
-import 'package:flutter/shell.dart';
 import 'package:mojo/core.dart' as core;
 import 'package:sky_services/flutter/platform/app_messages.mojom.dart';
 
+import 'shell.dart';
+
 // APIs for exchanging messages with the host application.
 
 ApplicationMessagesProxy _initHostAppMessagesProxy() {

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

@@ -7,7 +7,6 @@ import 'dart:ui' as ui;
 import 'dart:typed_data';
 
 import 'package:flutter/http.dart' as http;
-
 import 'package:mojo/core.dart' as core;
 import 'package:mojo_services/mojo/asset_bundle/asset_bundle.mojom.dart';
 
@@ -15,7 +14,7 @@ import 'fetch.dart';
 import 'image_cache.dart';
 import 'image_decoder.dart';
 import 'image_resource.dart';
-import 'binding.dart';
+import 'shell.dart';
 
 abstract class AssetBundle {
   ImageResource loadImage(String key);

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

@@ -2,51 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'package:flutter/shell.dart';
+import 'package:flutter/foundation.dart';
 
-export 'package:flutter/shell.dart';
-
-/// Base class for mixins that provide singleton services (also known as
-/// "bindings").
-///
-/// To use this class in a mixin, inherit from it and implement
-/// [initInstances()]. The mixin is guaranteed to only be constructed once in
-/// the lifetime of the app (more precisely, it will assert if constructed twice
-/// in checked mode).
-///
-/// The top-most layer used to write the application will have a
-/// concrete class that inherits from BindingBase and uses all the
-/// various BindingBase mixins (such as [Services]). For example, the
-/// Widgets library in flutter introduces a binding called
-/// [WidgetFlutterBinding]. The relevant library defines how to create
-/// the binding. It could be implied (for example,
-/// [WidgetFlutterBinding] is automatically started from [runApp]), or
-/// the application might be required to explicitly call the
-/// constructor.
-abstract class BindingBase {
-  BindingBase() {
-    assert(!_debugInitialized);
-    initInstances();
-    assert(_debugInitialized);
-  }
-
-  static bool _debugInitialized = false;
-
-  /// The initialization method. Subclasses override this method to hook into
-  /// the platform and otherwise configure their services. Subclasses must call
-  /// "super.initInstances()".
-  ///
-  /// By convention, if the service is to be provided as a singleton, it should
-  /// be exposed as `MixinClassName.instance`, a static getter that returns
-  /// `MixinClassName._instance`, a static field that is set by
-  /// `initInstances()`.
-  void initInstances() {
-    assert(() { _debugInitialized = true; return true; });
-  }
-
-  @override
-  String toString() => '<$runtimeType>';
-}
+import 'shell.dart';
 
 abstract class Services extends BindingBase {
   @override

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

@@ -4,12 +4,12 @@
 
 import 'dart:async';
 
+import 'package:flutter/foundation.dart';
 import 'package:mojo/mojo/url_request.mojom.dart' as mojom;
 import 'package:mojo/mojo/url_response.mojom.dart' as mojom;
 import 'package:mojo_services/mojo/url_loader.mojom.dart' as mojom;
 
-import 'assertions.dart';
-import '../http/mojo_client.dart';
+import '../http/mojo_client.dart'; // TODO(ianh): clean this up, see https://github.com/flutter/flutter/issues/2889
 
 export 'package:mojo/mojo/url_response.mojom.dart' show UrlResponse;
 

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

@@ -5,7 +5,7 @@
 import 'dart:async';
 import 'dart:ui' as ui show Image;
 
-import 'assertions.dart';
+import 'package:flutter/foundation.dart';
 
 /// A [ui.Image] object with its corresponding scale.
 ///

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

@@ -6,7 +6,7 @@ import 'dart:async';
 
 import 'package:sky_services/editing/editing.mojom.dart' as mojom;
 
-import 'binding.dart';
+import 'shell.dart';
 
 export 'package:sky_services/editing/editing.mojom.dart' show KeyboardType;
 

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

@@ -2,9 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-/// Manages connections with embedder-provided services.
-library shell;
-
 import 'dart:ui' as ui;
 
 import 'package:mojo/application.dart';

packages/flutter/lib/src/widgets/framework.dart

@@ -9,12 +9,12 @@ import 'dart:developer';
 import 'debug.dart';
 
 import 'package:flutter/rendering.dart';
-import 'package:flutter/services.dart';
+import 'package:flutter/foundation.dart';
 import 'package:meta/meta.dart';
 
 export 'dart:ui' show hashValues, hashList;
 export 'package:flutter/rendering.dart' show RenderObject, RenderBox, debugPrint;
-export 'package:flutter/services.dart' show FlutterError;
+export 'package:flutter/foundation.dart' show FlutterError;
 
 // KEYS
 

packages/flutter/lib/widgets.dart

@@ -50,4 +50,5 @@ export 'src/widgets/transitions.dart';
 export 'src/widgets/unique_widget.dart';
 export 'src/widgets/virtual_viewport.dart';
 
+export 'package:flutter/foundation.dart';
 export 'package:vector_math/vector_math_64.dart' show Matrix4;

packages/flutter/test/gestures/gesture_binding_test.dart

@@ -4,8 +4,8 @@
 
 import 'dart:ui' as ui;
 
+import 'package:flutter/foundation.dart';
 import 'package:flutter/gestures.dart';
-import 'package:flutter/services.dart';
 import 'package:mojo/bindings.dart' as mojo_bindings;
 import 'package:sky_services/pointer/pointer.mojom.dart';
 import 'package:test/test.dart';

packages/flutter/test/gestures/gesture_tester.dart

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'package:flutter/services.dart';
+import 'package:flutter/foundation.dart';
 import 'package:flutter/gestures.dart';
 
 class TestGestureFlutterBinding extends BindingBase with Gesturer { }

packages/flutter/test/scheduler/animation_test.dart

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'package:flutter/foundation.dart';
 import 'package:flutter/scheduler.dart';
-import 'package:flutter/services.dart';
 import 'package:test/test.dart';
 
 class TestSchedulerBinding extends BindingBase with Scheduler { }

packages/flutter/test/scheduler/scheduler_test.dart

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'package:flutter/foundation.dart';
 import 'package:flutter/scheduler.dart';
-import 'package:flutter/services.dart';
 import 'package:test/test.dart';
 
 class TestSchedulerBinding extends BindingBase with Scheduler { }

packages/flutter_test/lib/src/element_tree_tester.dart

@@ -4,9 +4,9 @@
 
 import 'dart:ui' as ui show window;
 
+import 'package:flutter/foundation.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/scheduler.dart';
-import 'package:flutter/services.dart';
 import 'package:flutter/widgets.dart';
 import 'package:quiver/testing/async.dart';
 import 'package:quiver/time.dart';