* Namespaces have been updated to reflect the move from //flutter/sky/shell to //flutter/shell.
* shell/BUILD.gn file has been split into smaller GN files for each subcomponent of the shell (common, GPU, diagnostic, testing).
* GN dependencies have been rewritten to stop exposing common shell dependencies as public. Duplicates have also been removed.
* GPU subcomponent has been updated make it more suitable for Vulkan integration.
* The GLFW backend has been resurrected.

Also, teach gn how to build application bundles.

After this patch, we're able to run spinning_square on Fuchsia. I've
left some TODO comments about some shortcuts I've taken that we'll need
to improve in the future.

We're now producing a flutter_content_handler binary for Fuchsia that
builds and links.

This pulled a refactoring of how we keep track of the primary threads.

This patch removes the //flutter/sky/engine dependency from //flutter/lib/ui,
which lets us build the bulk of the dart:ui library without needing to build
//flutter/sky/engine.

Doesn't quite work yet, but close. Fuchsia is on a newer Dart and will need a
couple patches before this will fully work.

* Create an Xcode project template for dynamic service creation.

The `create_native_service_sdk.py` will be run on the buildbot similar
to `create_ios_sdk.py`. This will create an Xcode project with both arm
and x64 assets that the user can use to fill in the service
implementation.

* Add the complete_static_lib property to sdk_lib_archive in
dynamic/BUILD.gn

It is called each time the embedder initializes a Flutter view controller. The Mac shell (which does not have a view controller), calls it before NSApplicationMain.

Common items like the base::AtExitManager and the platform message loop are stored in `EmbedderState`

We now use flutter.mojo instead.

Fixes Mac builds

Android and Linux builds.

Also fixes a couple of toolchain selection issues.

Instead of using a collection of Python scripts to generate the artifacts we
want to distribute from this repository, we should just use the build system.
This CL adds a top-level |dist| target that creates these artifacts in a "dist"
directory of the build output.

Sky itself does't need to depend on //services/debugger. That's already taken
care of by //services depending on //services/debugger. Also, add some direct
depenencies from //sky/sdk to the mojom interfaces used by //sky/sdk.

TBR=eseidel@google.com

Review URL: https://codereview.chromium.org/1232783006 .

Moving sky_viewer into services/sky is more consistent with how all the other
content handlers (e.g., dart, js, nacl, pdf, python) are organized.

TBR=eseidel@google.com

Review URL: https://codereview.chromium.org/1235093002 .

This target is unused.

TBR=eseidel@google.com

Review URL: https://codereview.chromium.org/1235053003 .

R=abarth@chromium.org, abarth

Review URL: https://codereview.chromium.org/1232483002 .

This interface is growing to expose many activity-related functions, more than
just intents.

R=eseidel@chromium.org, eseidel@google.com

Review URL: https://codereview.chromium.org/1223053002 .

Offline support isn't complete, but after this CL, SkyDemo.apk is able to start
and show some UI offline.

R=eseidel@chromium.org, eseidel@google.com

Review URL: https://codereview.chromium.org/1225883002.

This layer is no longer needed now that the new world is gone.

TBR=eseidel@google.com

Review URL: https://codereview.chromium.org/1210153009.

Instead of having a one-off //sky/apk/stocks, we now use the |sky_app| GN
template to create Stocks.apk directly from //sky/sdk/example/stocks.

TBR=eseidel@chromium.org

Review URL: https://codereview.chromium.org/1211883004.

This CL builds an APK for MineDigger that works offline. We use |sky_packager|
to snapshot the Dart code, which we then extract from the APK during startup.
If we succeed in extracting a snapshot, we load it by default.

TBR=eseidel@chromium.org

Review URL: https://codereview.chromium.org/1211253004.

This CL makes it possible to build sky_shell on Linux. It doesn't do much, but
it doesn't crash on startup. The goal is to evetually be able to test sky_shell
on the bots and to be able to run the test_sky on Mac.

R=eseidel@chromium.org

Review URL: https://codereview.chromium.org/1202323002.

This CL removes all C++11 library features from sky/tools/packager because we
can't use C++11 library features on Mac.

R=eseidel@chromium.org

Review URL: https://codereview.chromium.org/1198313004.

sky_packager requires C++11 and the Mac host toolchain can't handle C++11.

R=cstout@chromium.org, cstout@google.com

Review URL: https://codereview.chromium.org/1183223003.

sky_packager is a tool that generates a Dart script snapshot for Dart files
intended to run with dart:sky. I plan to use this tool to experiment with
startup performance.

R=jackson@google.com

Review URL: https://codereview.chromium.org/1178213003.

This makes the icons look nicer on the Nexus 5

I briefly played with trying to figure out which drawable_*
to use dynamically, but I couldn't seem to write a reasonable
solution which worked on both Desktop and my Nexus 5, leading
me to believe I didn't understand how it should work and just
went with xxhdpi for now.

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/1186633003.

We can use these intents to move the demo launcher to the new world.

R=eseidel@chromium.org

Review URL: https://codereview.chromium.org/1187583002.

Add a new target, sky_apk, that builds a minimal subset of the tree for creating working sky demo apks.

R=abarth@chromium.org, abarth@google.com

Review URL: https://codereview.chromium.org/1181893002.

Sky debugger is a native mojo app that puts up an http server and talks
to other mojo apps in response to http requests, allowing to
interactively start/stop tracing, profile, etc.

This is generally useful also when one does not run mojo_shell through
skydb, hence this patch pulls the debugger into services/debugger.

We can then add plumbing for running with the debugger in devtools.

Bug: domokit/devtools/#4.

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/1151573010

NOTE: This CL appears far larger than it actually is for two reasons:

1) Many files were moved around to use the Dart package directory structure.
2) Many .dart files had to have import paths updated.

- Organize mojo/public/dart so that it uses standard Dart package layout
- Organize mojo/dart/apptest so that it uses a standard Dart package layout
- Organize sky/sdk so that it uses a standard Dart package layout
- Create a mojo/testing package (used by unittests)
- Introduce the 'dart_pkg' gn rule which populates gen/Config/dart-pkg
- All internally vended Dart packages must have a corresponding dart_pkg rule
- It is now possible to use dependency_overrides: in pubspec.yaml to mix internal and external package dependencies (enables analyzer, editor, webstorm usage for internal developers).
- Package root for dart content handler ends with "packages/"
- Imports of mojo package uris no longer need the "public/dart"
- mojo/public/tools/dart_package.py is a clone of mojo/public/tools/gn/zip.py
- Sky tests no longer run 'deploy_sdk' script.

R=eseidel@chromium.org

Review URL: https://codereview.chromium.org/1132063007