Fire CanPlayThrough immediately for local and streaming media files

Changes DownloadRateMonitor logic to know to immediately fire CanPlayThrough
for media files with local sources, including local webcam streams. Renamed
the concept of "loaded" source to "local" source in the media pipeline for
clarity.

Also updated the DownloadRateMonitor logic slightly to lean toward optimism
in firing CanPlayThrough, including firing the event immediately for streaming
media.

BUG=105163
TEST=media_unittests,test_shell_tests, wjia's media stream test page works

Review URL: http://codereview.chromium.org/8661002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@112560 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 7 insertions, 0 deletions

diff --git a/media/base/demuxer.h b/media/base/demuxer.h
index a75f248..972d250 100644
--- a/media/base/demuxer.h
+++ b/media/base/demuxer.h
@@ -61,6 +61,13 @@ class MEDIA_EXPORT Demuxer
   // approximated. Returns 0 if it is unknown.
   virtual int GetBitrate() = 0;
 
+  // Returns true if the source is from a local file or stream (such as a
+  // webcam stream), false otherwise.
+  virtual bool IsLocalSource() = 0;
+
+  // Returns true if seeking is possible; false otherwise.
+  virtual bool IsSeekable() = 0;
+
  protected:
   Demuxer();
   FilterHost* host() { return host_; }