Chromium side changes for enabling VP8 and WebM support.

DEPS

 vars = {
   "webkit_trunk":
   "http://svn.webkit.org/repository/webkit/trunk",
   "webkit_revision": "59762",
-  "ffmpeg_revision": "46128",
+  "ffmpeg_revision": "47712",
   "skia_revision": "562",
   "chromium_git": "http://src.chromium.org/git",
   "swig_revision": "40423",
   "nacl_revision": "2235",
+  "libvpx_revision": "47701",
 }
 
 deps = {
   "src/breakpad/src":
     "http://google-breakpad.googlecode.com/svn/trunk/src@568",
 
   "src/build/util/support":
     "/trunk/deps/support@20411",
 
   "src/googleurl":
@@ skipping 115 matching lines @@
     Var("webkit_trunk") + "/LayoutTests/websocket/tests/workers@" +
     Var("webkit_revision"),
 
   "src/third_party/swig/Lib":
     "/trunk/deps/third_party/swig/Lib@" + Var("swig_revision"),
 
   "src/third_party/ffmpeg/source/patched-ffmpeg-mt":
     "/trunk/deps/third_party/ffmpeg/patched-ffmpeg-mt@" +
     Var("ffmpeg_revision"),
 
+  "src/third_party/libvpx":
+    "/trunk/deps/third_party/libvpx@" +
+    Var("libvpx_revision"),
+
   "src/third_party/ppapi":
     "http://ppapi.googlecode.com/svn/trunk@44",
 }
 
 
 deps_os = {
   "win": {
     "src/chrome/tools/test/reference_build/chrome":
       "/trunk/deps/reference_builds/chrome@41984",
 
@@ skipping 106 matching lines @@
     "action": ["python", "src/build/gyp_chromium"],
   },
   {
     # Workaround XCode dependecies problem.
     # TODO(bradnelson): remove this when fixed.
     "pattern": ".",
     "action": ["python",
                "src/build/mac/clobber_generated_headers.py"],
   },
 ]