This reverts commit d16ba48e.

The `ForwardingGestureRecognizers` to have back reference to the `PlatformViewsController` so it can access `FlutterViewController` when its available  (#20708)

The data race: gl_surface_fbo_frame_infos_ in the test context to was appended
to on the raster task runner but read on the platform task runner. This is now
sidestepped by using a callback and pushing that responsibility to the test.
Setting the callback is guarded behind a mutex.

The race condition: The assertions were previously run when the UI thread was
done generating the frames. However, the assertions were run on the results
collected on the raster thread in response the frame requests from UI thread.
Just run the assertions on the raster thread directly.

Fixes https://github.com/flutter/flutter/issues/64344

* Add native stacktrace on iOS

* Add native stacktrace on Android

* format and changing naming to errorWithCode on iOS

* reformat

* Remove stacktrace from decodeEnvelope, not needed.

* Separate encodeErrorEnvelopeWithStacktrace with original encode function

* Add unit tests

* re-format

* change comments for stacktrace

* Remove changes for iOS
Co-authored-by: NBen Li <libe@google.com>

The Windows embedding was based on the GLFW embedding, which grew
organically from a singe-file implementation that used structs to manage
all of the important state. It is in the process of being converted to a
cleaner object-based architecture, but currently it is a hybrid of
objects and structs that have redundant data, making it very prone to
errors of forgetting to update pointers in multiple locations.

This reduces the remaining structs to only a single pointer to the
larger object that manages the responsibilities that handle is
associated with, so that there is no need to wire things together in
multiple places.

For now they continue to exist as projections of the larger objects, but
that will be eliminated over time by having an object structure that
better reflects the API structure.

Fixes https://github.com/flutter/flutter/issues/64250

The response APIs for method channels and event channels used pointers
for optional parameters; this kept the API surface simple, but meant
that they couldn't take rvalues. As a result, returning success values
or error details often took an extra line, declaring a variable for the
result just to have something to pass the address of.

This converts them to using references, with function overloading to
allow for optional parameters, so that values can be inlined.

For now the pointer versions are still present, so that conversion can
be done before it becomes a breaking change; they will be removed soon.

Part of https://github.com/flutter/flutter/issues/63975

Fix flutter#40068 Redraw issues on resize/minimize/maximize on Windows and startup in release (#20357)

* Fix redraw issues

* Address CR feedback.

* Fix build

* CR feedback

Missing default focus when navigating to a page with no SemanticsNode that sets namesRoute:true (#20516)

* Hint the VM when a layer or picture goes out of scope

Skia is removing the ctors on these structs so removing them.

Adds APIs for runners to delegate WindowProc handlers into the Flutter
engine, and for plugins to register as possible delegates.

This allows for plugins to alter top-level window behavior in ways that
can only be done from the WindowProc, such as resize control. This
functionality remains entirely on the native side, so is synchronous.

Part of https://github.com/flutter/flutter/issues/53168

This reverts commit 9333b7c1.

Queries the system list of user-preferred languages, and sends it to the
engine just after starting it up.

Windows portion of https://github.com/flutter/flutter/issues/45152

Relands https://github.com/flutter/engine/pull/20399

Makes BinaryMessenger available from FlutterEngine, rather than just the plugin registrar. This allows for method channels directly in applications without building them as plugins, and matches the other platforms.

Requires some restructuring of code and GN targets in the client wrappers to make the internals in the shared section usable by the implementations of platform-specific parts of the wrappers. Also fixes a latent issue with EnableInputBlocking symbols being declared but not defined for Windows that came up during testing of the restructing.

Fixes https://github.com/flutter/flutter/issues/62871

This reverts commit 7fa21a45.

Makes BinaryMessenger available from FlutterEngine, rather than just the plugin registrar. This allows for method channels directly in applications without building them as plugins, and matches the other platforms.

Requires some restructuring of code and GN targets in the client wrappers to make the internals in the shared section usable by the implementations of platform-specific parts of the wrappers. Also fixes a latent issue with EnableInputBlocking symbols being declared but not defined for Windows that came up during testing of the restructuring.

Fixes https://github.com/flutter/flutter/issues/62871

FlutterViewControllers.

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

* Handle glfwGetPrimaryMonitor returning nullptr

[glfwGetPrimaryMonitor](https://www.glfw.org/docs/3.3/group__monitor.html#ga721867d84c6d18d6790d64d2847ca0b1) may return NULL in non-error cases when no monitor is found. This started to happen recently with an update to the linux distribution, see internal b/162545223.

Handling this case avoids a crash and instead assumes a pixel density.

controllers instead of views.

hasStrings message for checking for pasteable clipboard contents without actually reading them, for iOS14 clipboard alerts.