This was only necessary when the Engine had to build in multiple buildroots
where the sources where checked out at different paths relative to the
buildroot. This is no longer the case and there are already cases GN rules
have been written that mix and match variable usage with the direct
specification of the path to the Flutter sources relative to the sole buildroot.

Revert "Migrate flutter_runner from flutter_runner::{Thread,Loop} to fml::{Thread,MessageLoop} (#15118)" (#16277)

This reverts commit 41e8ed07.

The current count is determined from std::thread::hardware_concurrency which can
return zero. Even in such cases, the implementation may not return a loop with
no workers. There are numerous components that depend on having non-zero workers
in the queue.

`FlutterEnginePostCallbackOnAllNativeThreads` schedule a callback to be run on
all engine managed threads. The engine will attempt to service this callback the
next time the message loops for each managed thread is idle. Since the engine
manages the entire lifecycle of multiple threads, there is no opportunity for
the embedders to finely tune the priorities of threads directly, or, perform
other thread specific configuration (for example, setting thread names for
tracing). This callback gives embedders a chance to affect such tuning.

Fixes flutter/flutter#49551
Fixes b/143774406
Fixes b/148278215
Fixes b/148278931

Tonic used to be used by multiple consumers outside of Flutter Engine. Due to
this, it has an unnecessary abstraction layer as well as utilities duplicated in
FML and other engine subsystems. The sole user of Tonic is now the Flutter
Engine. It is intended that the Flutter Engine team now owns this subsystem,
remove unnecessary utilities and document the headers. This is the first step in
the transition. No history is being imported as the initial history was already
lost in the transition of this component to fuchsia.googlesource. As this
component was unmaintained there, I could see no additional value in importing
the history of the patches there.

No functional change. Just moved the repo from //third_party to
//flutter/third_party and updates GN refs.

Calling Dart_TimelineEvent has a performance cost, and the APIs for collecting
timeline events are not available in release mode.

Revert "Migrate flutter_runner from flutter_runner::{Thread,Loop} to fml::{Thread,MessageLoop} (#15118)" (#15903)

This reverts commit a50f1ef5.

When running on Fuchsia, respect the argument values that Skia passes
into the Flutter implementation of the |SkEventTracer| interface.

Bug: https://github.com/flutter/flutter/issues/48864

This is a non-breaking addition to the stable Flutter Embedder API and exposes a
subset of the functionality provided by Dart_PostCObject API in a stable and
tested manner to custom embedder implementations.

Send port acquisition can currently be done as described in the unit-test but
there may be opportunities to extend this API in the future to access ports more
easily or create ports from the native side.

The following capabilities of the the Dart_PostCObject API are explicitly NOT
exposed:
* Object arrays: This allows callers to create complex object graphs but only
  using the primitives specified in the native API. I could find no current use
  case for this and would have made the implementation a lot more complex. This
  is something we can add in the future if necessary however.
* Capabilities and ports: Again no use cases and I honestly I didn’t understand
  how to use capabilities. If needed, these can be added at a later point by
  appending to the union.

Fixes https://github.com/flutter/flutter/issues/46624
Fixes b/145982720

This gives us a time closer to when the frame will be rendered on
screen.

Fixes: https://github.com/flutter/flutter/issues/10850

This reverts commit 6c605f8a.

* Revert "Add flow test fixtures and tests (#13986)"

This reverts commit 620f5281.

* Revert "Dynamically determine whether to use offscreen surface based on need (#13976)"

This reverts commit a86ef946.

The converters are still in a separate target that must be included manually. This allows targets that depend on FML but not Dart runtime not have to depend on the runtime.

Adds a test that includes this target and tests image decompression from assets. There is also a test for the standalone DartConvertor in shell_unittests but not in fml_unittests be cause FML uni-tests cannot yet launch a VM. I will work on adding fixtures for those.

* Add fuchsia MessageLoopImpl; fix several tests

Moved our code to passing functions by const ref

Add fml_tests target for the fml unit tests on Fuchsia

The fd passed to fdopendir will be unusable afterward.  Using a duplicate
preserves the validity of the original directory fd passed to VisitFiles.

Fixes https://github.com/flutter/flutter/issues/43844

This reverts commit 4d553cfe.

This re-enables thread safety checks for WeakPtr. WeakPtrs can't be used on a thread other than the one the WeakPtrFactory was created on.

This fixes the unit tests and adds a getUnsafe() method to WeakPtr to work around the remaining unresolved locations where we are using WeakPtr unsafely.

Fixes https://github.com/flutter/flutter/issues/42704.

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

For https://github.com/flutter/flutter/issues/40686

Unit tests added:
- CacheSkSLWorks
- VisitFilesCanBeCalledTwice
- CanListFilesRecursively

For https://github.com/flutter/flutter/issues/32170

This is to enable reading back SkSL persistent cache filenames
and decode them as SkData.

So we can get the correct graph on 90fps/120fps devices :)

See https://github.com/flutter/flutter/issues/37888