Remove mock_ffmpeg and update media unittests.

media/filters/ffmpeg_glue.h

Index: media/filters/ffmpeg_glue.h
diff --git a/media/filters/ffmpeg_glue.h b/media/filters/ffmpeg_glue.h
index a98c50219d1445083f086af4e8637ab4770a7ead..0e91fd3df62d77778c00c214b397b89031283b6b 100644
--- a/media/filters/ffmpeg_glue.h
+++ b/media/filters/ffmpeg_glue.h
@@ -32,15 +32,15 @@
 #include "base/memory/singleton.h"
 #include "base/synchronization/lock.h"
 
+struct URLProtocol;
+
 namespace media {
 
 class FFmpegURLProtocol {
  public:
-  FFmpegURLProtocol() {
-  }
+  FFmpegURLProtocol() {}
 
-  virtual ~FFmpegURLProtocol() {
-  }
+  virtual ~FFmpegURLProtocol() {}
 
   // Read the given amount of bytes into data, returns the number of bytes read
   // if successful, kReadError otherwise.
@@ -99,6 +99,9 @@ class FFmpegGlue {
   typedef std::map<std::string, FFmpegURLProtocol*> ProtocolMap;
   ProtocolMap protocols_;
 
+  friend class FFmpegGlueTest;
+  static URLProtocol* url_protocol();
+
   DISALLOW_COPY_AND_ASSIGN(FFmpegGlue);
 };