Using WeakPtr for requests to MediaStreamDispatcher.

This is to ensure no dangling pointers to MediaStreamImpl (and other requesters). It's one of several fixes for the bug. No actual crash or issue has been reported that this CL fixes; it's for removing potential issues.

BUG=112408

Review URL: https://chromiumcodereview.appspot.com/9903014

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@131330 0039d316-1c4b-4281-b951-d872f2087c98
8 files changed