More media::PipelineImpl cleanup, this time focusing on not taking down the render process.

More media::PipelineImpl cleanup, this time focusing on not taking down the render process.

Specifically, if the pipeline hasn't started we should fail gracefully and not DCHECK.  Volume and playback rate are now allowed to be set if the pipeline isn't running, and filters will now receive a call to SetVolume() and SetPlaybackRate() with the initial values when the pipeline has fully initialized.

Added tests and expectations for all of this and ran valgrind to verify that we were indeed leaking memory (now fixed).

BUG=16009, 13902
TEST=media_unittests, layout tests

[Alpha Left Google, 2009-07-11 02:05:36]

LGTM.

http://codereview.chromium.org/149500/diff/5/6
File media/base/pipeline_impl.cc (right):

http://codereview.chromium.org/149500/diff/5/6#newcode82
Line 82: scoped_ptr<PipelineCallback> callback(start_callback);
good catch on leak! :)

http://codereview.chromium.org/149500/diff/5/7
File media/base/pipeline_impl.h (right):

http://codereview.chromium.org/149500/diff/5/7#newcode187
Line 187: // Notifications that the client has changed the playback rate/volume.
Notifies?

[scherkus (not reviewing), 2009-07-11 02:39:58]

http://codereview.chromium.org/149500/diff/5/7
File media/base/pipeline_impl.h (right):

http://codereview.chromium.org/149500/diff/5/7#newcode187
Line 187: // Notifications that the client has changed the playback rate/volume.
On 2009/07/11 02:05:36, Alpha wrote:
> Notifies?

Done.