Add missing 'virtual'.

BUG=none
TEST=none

Review URL: http://codereview.chromium.org/8893020

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@113899 0039d316-1c4b-4281-b951-d872f2087c98

content/renderer/renderer_gpu_video_decoder_factories.h

@@ -29,7 +29,7 @@ class RendererGpuVideoDecoderFactories
 
   virtual ~RendererGpuVideoDecoderFactories();
 
-  media::VideoDecodeAccelerator* CreateVideoDecodeAccelerator(
+  virtual media::VideoDecodeAccelerator* CreateVideoDecodeAccelerator(
       media::VideoDecodeAccelerator::Profile profile,
       media::VideoDecodeAccelerator::Client* client) OVERRIDE;