Support for:
1. Capability enumeration, negotiation and managment.
2. Generic client-side extensions, similar to HostExtension model in Chromoting host.
3. Interaction with Chromoting host's CastExtension and support for Cast Sender API
(prototype for Cast support).
Note:
The android app has four new dependencies: v4 support, v7 appcompat, v7 mediarouter,
google play services. The first three are in third_party/android_tools/,
but the last isn't. See crbug.com/403948. This CL will not break any builds
since the code is behind a gyp flag in remoting.gyp.
Review URL: https://codereview.chromium.org/451973002
Cr-Commit-Position: refs/heads/master@{#289897}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@289897 0039d316-1c4b-4281-b951-d872f2087c98
5f87658350