Hook up WebRTC logging extension API to the underlying functionality.

The API skeleton CL landed previously: https://chromiumcodereview.appspot.com/23885002/

In the CL:
- Hook up the API to the logging functionality.
- Changes to the logging functionality to allow for new API features.
- Make RenderProcessHost a SupportsUserData, to be able to associate a logging handler host with it.
- Made a fix in base/supports_user_data.h.
- Removal of the old way of enabling logging via the JS PeerConnection constructor.
- Refactorings due to the new API features and removals.

TBR=jochen@chromium.org (for chrome/common/media/webrtc_logging_messages.h)
BUG=298158

Review URL: https://codereview.chromium.org/23691066

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226805 0039d316-1c4b-4281-b951-d872f2087c98
[NaCl SDK] Fix a few bugs in the debugging example.

1) The malloc in DumpJson was too small, by one byte.
2) The debugging example assumed that the map file would be generated by "nm",
but now we always generate a map file, via the linker. The formats are
different, so the example wouldn't find any symbols.

BUG=none
R=noelallen@chromium.org

Review URL: https://codereview.chromium.org/24462002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226806 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226806