Cast:Fix threading mismatch in AudioReceiver

This cl guarantees that logging and GetPlayoutDelay are called on the appropriate (MAIN) thread. 

BUG= 323703

Review URL: https://codereview.chromium.org/102943002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238638 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 238638
Add .shared field to drive::ResourceEntry.

Just adding the field. Actual filling code will come next.

BUG=264812
R=hashimoto@chromium.org

Review URL: https://codereview.chromium.org/103833002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238639 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 238639