This requires adding a way for platform services (namely SystemChromeImpl) to
listen for activity lifecycle events

Fixes https://github.com/flutter/flutter/issues/4885

Also provide an API for obtaining the path where the app bundle was extracted

- Pick up fix for 64-bit AOT/caching-JIT snapshots.

Previously we enabled accessibility unconditionally on iOS, which is more
expensive than necessary. We still enable it unconditionally on the simulator
because there's no API for determining whether accessibility is needed on the
simulator.

Fixes #4849

Package map entries can contain relative paths.
See related commit: d7d99c62

Previously we failed to copy these files to the correct place.

Added a section which explains how to get `dart:ui` changes.

Add a --pause-isolates-on-start flag to the flutter mojo content
handler to match the one that's supported by the dart mojo content
handler.

Fixes: https://github.com/flutter/flutter/issues/4802

These classes now use the same terminology and work in the same way.
Also, change semantics.mojom to use an enumeration of actions instead of
having a separate method per action. This will hopefully scale better.

- clustered serialization (dart-lang/sdk@524fbc1e0f9d61ff5da69bbed2b35745528de945)
 - background finalization (flutter/flutter#3804)

Avoid re-entering the message loop while reloading. Fixes on stack reloading in Flutter embedder. (#2775)

https://github.com/flutter/flutter/issues/4560

* Update to mojo fd8d18dbf7a4f9ed8a607648cca6d2c595b1c580

* Update mojo_sdk

* Update to account for Mojo API changes

* Backport to older base

Fixes #69

It's empty and is easily confused with onPostResume

This will make it simpler to write listeners that can be reused in multiple
applications.

I noticed this while doing the libjpeg_turbo roll.

* Update libjpeg_turbo

* Update our libjpeg_turbo BUILD.gn file

This brings in this file from upstream:
https://chromium.googlesource.com/chromium/src/+/master/build/secondary/third_party/libjpeg_turbo/BUILD.gn

* We don't always build with libjpeg

...so the libjpeg target isn't always available.

Fix leaky descriptor in dart_init and use the correct macro to handle EINTRs on close syscall wrappers. (#2765)

* Use IGNORE_EINTR instead of HANDLE_EINTR when using the `close` syscall wrapper.
* Don't leak the file descriptor used to memory map Dart related artifacts.

Updating base turns out to be more complicated than I thought.

This reverts commit daa822aa.
This reverts commit c38428c7.
This reverts commit 4b73a8a0.

Update base, gn, and their clients.

These files are generated to different paths now.

The upstream mojo.git no longer contains this code.