Enable media in default GN build.

DEPS

 # This file is automatically processed to create .DEPS.git which is the file
 # that gclient uses under git.
 #
 # See http://code.google.com/p/chromium/wiki/UsingGit
 #
 # To test manually, run:
 #   python tools/deps2git/deps2git.py -o .DEPS.git -w <gclientdir>
 # where <gcliendir> is the absolute path to the directory containing the
 # .gclient file (the parent of "src").
 #
@@ skipping 202 matching lines @@
   # Make sure you update the two functional.DEPS and webdriver.DEPS too.
   "src/third_party/webdriver/pylib":
     (Var("googlecode_url") % "selenium") + "/trunk/py@18337",
 
   "src/third_party/libvpx":
     "/trunk/deps/third_party/libvpx@" +
     Var("libvpx_revision"),
 
   "src/third_party/ffmpeg":
     Var("chromium_git") +
-    "/chromium/third_party/ffmpeg.git@f620cda6d1661f1b2f3214d17b9a254f5c89225f",
+    "/chromium/third_party/ffmpeg.git@4b7b36f956209fad838ad87d0129130713fbb00c",
 
   "src/third_party/libjingle/source/talk":
     (Var("googlecode_url") % "webrtc") + "/trunk/talk@" +
     Var("webrtc_revision"),
 
   "src/third_party/usrsctp/usrsctplib":
     (Var("googlecode_url") % "sctp-refimpl") +
     "/trunk/KERN/usrsctp/usrsctplib@8912",
 
   "src/third_party/libsrtp":
@@ skipping 583 matching lines @@
                 "src/third_party/apache-win32",
     ],
   },
   {
     # A change to a .gyp, .gypi, or to GYP itself should run the generator.
     "name": "gyp",
     "pattern": ".",
     "action": ["python", "src/build/gyp_chromium"],
   },
 ]