Android Embedding PR 13: Integrated text input, keyevent input, and some other channel comms in FlutterView. (#7979)

Android Embedding PR 9: Introduce an AndroidTouchProcessor to convert MotionEvents to Flutter touch data. (#7947)

occured -> occurred
preceeded -> preceded

Some embedders prefer to minimise the number of semantics node/custom
action updates sent back to the host platform -- for example due to
expensive serialisation mechanisms, etc.

This patch provides a 'batch end' signal that provides embedders with an
indication of when a self-consistent set of semantics node or custom action
updates have been sent.

We overload the node/action ID with information that conveys a batch end
by using an ID (-1) that is never allotted to semantics nodes by the
framework.

Fixes https://github.com/flutter/flutter/issues/28490

Adds an option to enable mouse tracking, which will send
add/hover/remove events to the Flutter engine.

Link dart:* sources into engine for debugger source support

Currently, dart:* libraries appear to have no source in
debuggers like Observatory. With this change, these sources will be
available in debug mode applications. Sources for dart:* libraries are
lazily loaded on a script-by-script basis.

Refer to https://dart-review.googlesource.com/c/sdk/+/93375 for the Dart
SDK change.

If an app is using retainFlutterNativeView or a plugin wants to keep the
FlutterNativeView active, then the FlutterNativeView should not drop its
handle to the corresponding native platform view.

Fixes https://github.com/flutter/flutter/issues/26931

Correct struct members whose names were camelCase rather than
snake_case. This is a breaking API change, but does not break ABI.

[Configuration.getLocales()][1] was added in API level 24. 
For earlier versions, we instead return only the current locale.

Fixes https://github.com/flutter/flutter/issues/28321

[1]: https://developer.android.com/reference/android/content/res/Configuration#getLocales()

Android Embedding PR 6: Introduce FlutterView structure with FlutterSurfaceView and FlutterTextureView. (#7896)

This will help further changes when we pull other artifacts into the bundle.

This will reduce 1 render target switch when preroll paints some raster
cache.

Fixes https://github.com/flutter/flutter/issues/28240

Fixes https://github.com/flutter/flutter/issues/28283

Fixes https://github.com/flutter/flutter/issues/28278

This breaks MSVC:
```
[3049/3506] CXX obj/flutter/shell/gpu/gpu_surface_gl.gpu_surface_gl_delegate.obj
FAILED: obj/flutter/shell/gpu/gpu_surface_gl.gpu_surface_gl_delegate.obj
ninja -t msvc -e environment.x64 -- E:\b\c\goma_cache\client/gomacc.exe "E:\b\depot_tools\win_toolchain\vs_files\3bc0ec615cf20ee342f3bc29bc991b5ad66d8d2c\VC\Tools\MSVC\14.14.26428\bin\HostX64\x64/cl.exe" /nologo /showIncludes /FC @obj/flutter/shell/gpu/gpu_surface_gl.gpu_surface_gl_delegate.obj.rsp /c ../../flutter/shell/gpu/gpu_surface_gl_delegate.cc /Foobj/flutter/shell/gpu/gpu_surface_gl.gpu_surface_gl_delegate.obj /Fdobj/flutter/shell/gpu/gpu_surface_gl_cc.pdb
e:\b\rr\tmpahx5uo\w\src\flutter\shell\gpu\gpu_surface_gl_delegate.cc(70): error C2059: syntax error: '.'
e:\b\rr\tmpahx5uo\w\src\flutter\shell\gpu\gpu_surface_gl_delegate.cc(71): error C2143: syntax error: missing ';' before '}'
e:\b\rr\tmpahx5uo\w\src\flutter\shell\gpu\gpu_surface_gl_delegate.cc(76): error C2061: syntax error: identifier 'ProcResolverContext'
e:\b\rr\tmpahx5uo\w\src\flutter\shell\gpu\gpu_surface_gl_delegate.cc(78): error C3536: 'proc_resolver_context': cannot be used before it is initialized
e:\b\rr\tmpahx5uo\w\src\flutter\shell\gpu\gpu_surface_gl_delegate.cc(78): error C2227: left of '->resolver' must point to class/struct/union/generic type
e:\b\rr\tmpahx5uo\w\src\flutter\shell\gpu\gpu_surface_gl_delegate.cc(78): note: type is 'int'
e:\b\rr\tmpahx5uo\w\src\flutter\shell\gpu\gpu_surface_gl_delegate.cc(82): error C2059: syntax error: 'if'
e:\b\rr\tmpahx5uo\w\src\flutter\shell\gpu\gpu_surface_gl_delegate.cc(82): error C2143: syntax error: missing ';' before '{'
e:\b\rr\tmpahx5uo\w\src\flutter\shell\gpu\gpu_surface_gl_delegate.cc(82): error C2447: '{': missing function header (old-style formal list?)
e:\b\rr\tmpahx5uo\w\src\flutter\shell\gpu\gpu_surface_gl_delegate.cc(87): error C2059: syntax error: 'if'
e:\b\rr\tmpahx5uo\w\src\flutter\shell\gpu\gpu_surface_gl_delegate.cc(87): error C2143: syntax error: missing ';' before '{'
e:\b\rr\tmpahx5uo\w\src\flutter\shell\gpu\gpu_surface_gl_delegate.cc(87): error C2447: '{': missing function header (old-style formal list?)
e:\b\rr\tmpahx5uo\w\src\flutter\shell\gpu\gpu_surface_gl_delegate.cc(91): error C2059: syntax error: '('
e:\b\rr\tmpahx5uo\w\src\flutter\shell\gpu\gpu_surface_gl_delegate.cc(91): error C2059: syntax error: ')'
e:\b\rr\tmpahx5uo\w\src\flutter\shell\gpu\gpu_surface_gl_delegate.cc(92): error C2059: syntax error: 'return'
e:\b\rr\tmpahx5uo\w\src\flutter\shell\gpu\gpu_surface_gl_delegate.cc(95): error C2653: 'GPUSurfaceGLDelegate': is not a class or namespace name
e:\b\rr\tmpahx5uo\w\src\flutter\shell\gpu\gpu_surface_gl_delegate.cc(95): error C2270: 'GetGLInterface': modifiers not allowed on nonmember functions
e:\b\rr\tmpahx5uo\w\src\flutter\shell\gpu\gpu_surface_gl_delegate.cc(96): error C3861: 'GetGLProcResolver': identifier not found
e:\b\rr\tmpahx5uo\w\src\flutter\shell\gpu\gpu_surface_gl_delegate.cc(96): error C3861: 'CreateGLInterface': identifier not found
e:\b\rr\tmpahx5uo\w\src\flutter\shell\gpu\gpu_surface_gl_delegate.cc(100): error C2653: 'GPUSurfaceGLDelegate': is not a class or namespace name
e:\b\rr\tmpahx5uo\w\src\flutter\shell\gpu\gpu_surface_gl_delegate.cc(101): error C3861: 'CreateGLInterface': identifier not found
e:\b\rr\tmpahx5uo\w\src\flutter\shell\gpu\gpu_surface_gl_delegate.cc(104): error C2059: syntax error: '}'
e:\b\rr\tmpahx5uo\w\src\flutter\shell\gpu\gpu_surface_gl_delegate.cc(104): error C2143: syntax error: missing ';' before '}'
```

Flutter's accessibility APIs consist of three main calls from the
embedder to the Dart application:

  1. FlutterEngineUpdateSemanticsEnabled: enables/disables semantics support.

  2. FlutterEngineUpdateAccessibilityFeatures: sets embedder-specific
     accessibility features.

  3. FlutterEngineDispatchSemanticsAction: dispatches an action (tap,
     long-press, scroll, etc.) to a semantics node.

and two main callbacks triggered by Dart code:

  1. FlutterUpdateSemanticsNodeCallback: notifies the embedder of
     updates to the properties of a given semantics node.

  2. FlutterUpdateSemanticsCustomActionCallback: notifies the embedder
     of updates to custom semantics actions registered in Dart code.

In the Flutter framework, when accessibility is first enabled, the
embedder will receive a stream of update callbacks notifying the
embedder of the full semantics tree. On further changes in the Dart
application, only updates will be sent.

Fixes https://github.com/flutter/flutter/issues/28229

Merging back in after reversion. Fixed some messaging issues in FlutterNativeView and corrected some message parsing.

This reverts commit f4fba6d7.

This reverts commit 0d6ff166.

Adds 'add', 'remove', and 'hover' to the set of pointer phases that are
available to embedders. This is necessary for them to send hover events
to the engine.

This reverts commit d48de7a3.

From build log:
```
../../flutter/shell/platform/android/io/flutter/view/FlutterView.java:95: error: cannot find symbol
    private final LocalizationChannel localizationChannel;
                  ^
  symbol:   class LocalizationChannel
  location: class FlutterView
../../flutter/shell/platform/android/io/flutter/view/FlutterView.java:172: error: cannot find symbol
        localizationChannel = new LocalizationChannel(dartExecutor);
                                  ^
  symbol:   class LocalizationChannel
  location: class FlutterView
2 errors
```

This reverts commit 256db4bc.

The shell was already designed to cleanly shut down the VM but it couldnt
earlier as |Dart_Initialize| could never be called after a |Dart_Cleanup|. This
meant that shutting down an engine instance could not shut down the VM to save
memory because newly created engines in the process after that point couldn't
restart the VM. There can only be one VM running in a process at a time.

This patch separate the previous DartVM object into one that references a
running instance of the DartVM and a set of immutable dependencies that
components can reference even as the VM is shutting down.

Unit tests have been added to assert that non-overlapping engine launches use
difference VM instances.