Part 2: Plumb render view ID to content::MediaObserver

Part 2: Plumb render view ID to content::MediaObserver

This is part 2 of the work to add audio indicator to tabs.

This CL plubms the render view ID from render host to the browser. chrome://media-internals now shows tab titles next to each audio stream.

BUG=64215
TEST=Go to a website playing audio. Open chrome://media-internals and verify that tab titles are displayed.

[tommi (sloooow) - chröme, 2012-07-31 10:21:43]

Great stuff.  I see Chris' point on now passing three ids to all the functions
<insert meme here> but I don't see how we can easily avoid that without
refactoring the code quite a bit.  I don't think that's important enough to
block this cl, so LGTM.  I suspect we'll refactor bits of this code soon anyway.

[sail, 2012-08-01 00:04:48]

Rebased on top of changes to part 1.
Note, I removed the "void* host" argument. This was being used as a unique ID
for a render process but now that we have the process ID we don't need it.

[tommi (sloooow) - chröme, 2012-08-01 11:10:41]

thanks for the update.  looks better with the host pointer removed.