* Revert "Fix documentation build for window changes. (#21780)"

This reverts commit 931a0468.

* Revert "Migration to PlatformDispatcher and multi-window (#20496)"

This reverts commit 85b0031f.

This is a PR for converting the dart:ui code in the engine to use a multi-window API. The goal here is to convert from the window singleton to an API that has the concept of multiple windows. Also, I'm matching up the new PlatformDispatcher class to talk directly to the PlatformConfiguration class in the engine. I'm not attempting to actually enable creating multiple windows here, just migrate to an API that has a concept of multiple windows. The multi-window API in this PR currently only ever creates one window.

The design doc for this change is here.

The major changes in this PR:

Move the platfom-specific attributes out of Window, and into the new PlatformDispatcher class that holds all of the platform state, so that the platform code need only update the configuration on this class.
Create FlutterView, FlutterWindow, and SingletonFlutterWindow classes to separate out the concepts of a view (of which there may be multiple in a window), a window (of which there may be multiple on a screen, and they host views), and a window where there is only ever expected to be one (this hosts the entire API of the former Window class, and will eventually be the type of the window singleton).
Next step after this PR lands:

Remove the Window class entirely (it is replaced by SingletonFlutterWindow). Some minor changes in the Framework are needed to switch to using SingletonFlutterWindow directly first.

The Window class still exists in this PR, but will be removed as soon as the framework is converted to point to the SingletonFlutterWindow class instead. They share the same API, just have different names (Window is currently a subclass of SingletonFlutterWindow). The intention is that the Window name will be freed up to use as a widget class name in the framework for managing windows. The singleton called window will remain, and keep the same API it has now.

Reland #19396 with a fix for improper scale that was affecting internal tests

Tested: Ran all unittests, ran internal tests, and ran workstation on Fuchsia
BUG: 53062, 53063

This reverts commit 12a37478.

The fuchsia code around metrics and sizing was just sending this
information through a side-channel, when the engine already had the
information available. So, delete all of it to make future CLs simpler.

Additionally, the SceneUpdateContext has many unneccesary dependencies
re: metrics and PaintTasks. Break those to make future CLs simpler.

Tested: Ran all unittests and ran workstation on Fuchsia
BUG: 53062, 53063

This fixes all of the lint errors in lib/ui, except for a few (three, I think) where it would have changed the API, converting non-const references to pointers. For those, I just did NOLINT on the particular line instead of ignoring the whole file.

* Revert "Do not register UI-related native functions in secondary isolates (#6401)"

This reverts commit 69ae5694 as it doesn't work when root and secondary isolates run in the same isolate group.

* Confirm it is root isolate that makes UI native calls.

* Fix format, UIDartState reference from Fuchsia source

* No UI isolate check for fuchsia calls

* Fix typo. Remove redundant runtime calls

Since this is currently only meant to be used by the embedding internally, the setter in Objective-C is only exposed via the FlutterDartProject private class extension. Unit tests have been added to the shell_unittests harness.

Fixes https://github.com/flutter/flutter/issues/37641

* Pass Android Q system gesture inset information from insets.systemGestureInsets to Window.systemGestureInsets

Using it, a Flutter app can monitor missing frames in the release mode, and a custom Flutter runner (e.g., Fuchsia) can add a custom FrameRasterizedCallback.

Related issues:
https://github.com/flutter/flutter/issues/26154
https://github.com/flutter/flutter/issues/31444
https://github.com/flutter/flutter/issues/32447

Need review as soon as possible so we can merge this before the end of May to catch the milestone.

Tests added:
* NoNeedToReportTimingsByDefault
* NeedsReportTimingsIsSetWithCallback
* ReportTimingsIsCalled
* FrameRasterizedCallbackIsCalled
* FrameTimingSetsAndGetsProperly
* onReportTimings preserves callback zone
* FrameTiming.toString has the correct format

This will need a manual engine roll as the TestWindow defined in the framework needs to implement onReportTimings.

Some components in the Flutter engine were derived from the forked blink codebase. While the forked components have either been removed or rewritten, the use of the blink namespace has mostly (and inconsistently) remained. This renames the blink namesapce to flutter for consistency. There are no functional changes in this patch.

We used to make tonic make the wrapper before the SendPlatformMessage invocation. However, tonic would not collect the wrapper before make the Dart API call to return the value from the native method. This is illegal and would trip an assertion in the Dart VM. A more systematic fix required reworking tonic to handle this case. However, to fix our illegal use of the Dart API now, this patch creates the wrapper manually in function scope.

Fixes https://github.com/flutter/flutter/issues/29058

This reverts commit 0b174017.

Re-land "Wrap the user entrypoint function in a zone with native exception callback. (#7512)" (#7551)

This reverts commit 4c135c29 and applies relevant fixes.

Revert "Wrap the user entrypoint function in a zone with native exception callback. (#7512)" (#7522)

This reverts commit 25559ed0.

Reason for revert: broken in AOT mode.

@pragma('vm:entry-point') placed on a function only instructs
the compiler to retain the function itself, but does not tell
compiler to generate and retain tear-off for this function.

In this PR _runMainZoned was marked as an entry-point but C++
code was trying to tear it off and use a closure, instead of
invoking it directly, which is not supported.

Keep a copy of each engine's description that can be accessed outside the engine's UI thread (#6885)

The service protocol's ListViews method needs to return description data for
each engine in the process.  Previously ListViews would queue a task to each
UI thread to gather this data.  However, the UI thread might be blocked from
executing tasks (e.g. if the Dart isolate is paused), resulting in a deadlock.

This change provides a copy of the engine's description data to the
ServiceProtocol's global list of engines, allowing ListViews to run without
accessing any UI threads.

Fixes https://github.com/flutter/flutter/issues/24400

An integration test will be added to the framework's repo as a followup.

Addresses flutter/flutter#22009

* Locale Passing

* Pass full locale list and script and variant codes to framework

* Working Android locale list passing and fallback

Reverts flutter/engine#5740

Toward no-copy loading of kernel.

This reverts commit 15b76dd3.