Roll libvpx 563c46:4e6bc0 //r291625:r291661

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 18 matching lines @@
   'webkit_trunk': 'http://src.chromium.org/blink/trunk',
   'nacl_trunk': 'http://src.chromium.org/native_client/trunk',
   'webkit_revision': '110f8a11d9b4a57f1df675746df777bcb67bf4ea', # 180973
   'chromium_git': 'https://chromium.googlesource.com',
   'chromiumos_git': 'https://chromium.googlesource.com/chromiumos',
   'pdfium_git': 'https://pdfium.googlesource.com',
   'skia_git': 'https://skia.googlesource.com',
   'boringssl_git': 'https://boringssl.googlesource.com',
   # After changing nacl_revision, run 'glient sync' and check native_client/DEPS
   # to update other nacl_*_revision's.
-  'libvpx_revision': '563c46bb2d0e5d5c8b7d2c6c0c50f0283e9087de', # r291625
+  'libvpx_revision': '4e6bc04ba5f53c570e057fe1df5c470a67aaf144', # r291661
   'sfntly_revision': '1bdaae8fc788a5ac8936d68bf24f37d977a13dac',
   'skia_revision': '6b0d6b43cf662735dc804d8142383452c7f246f9',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling Skia
   # and V8 without interference from each other.
   'v8_branch': 'trunk',
   'v8_revision': '946ae75ed85d2c5839a2d6630c4b443f0264e6e0', # from svn revision 23464
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling WebRTC
   # and V8 without interference from each other.
@@ skipping 742 matching lines @@
     # corresponding .py files have already been deleted.
     'name': 'remove_stale_pyc_files',
     'pattern': 'src/tools/.*\\.py',
     'action': [
         'python',
         'src/tools/remove_stale_pyc_files.py',
         'src/tools',
     ],
   },
 ]