Add unittest for H264BitReader.

content/common/gpu/media/h264_parser.h

Index: content/common/gpu/media/h264_parser.h
diff --git a/content/common/gpu/media/h264_parser.h b/content/common/gpu/media/h264_parser.h
index e64b1f307290c7667bff28efc985dd7e297c72a8..b60e1c6d954f9172bb2adab23b68d410185a4462 100644
--- a/content/common/gpu/media/h264_parser.h
+++ b/content/common/gpu/media/h264_parser.h
@@ -14,6 +14,8 @@
 #include "base/basictypes.h"
 #include "content/common/content_export.h"
 
+class H264BitReaderTest;
+
 namespace content {
 
 // For explanations of each struct and its members, see H.264 specification
@@ -301,11 +303,12 @@ class CONTENT_EXPORT H264Parser {
   Result ParseSEI(H264SEIMessage* sei_msg);
 
  private:
+  friend class ::H264BitReaderTest;
+
   // A class to provide bit-granularity reading of H.264 streams.
   // This is not a generic bit reader class, as it takes into account
   // H.264 stream-specific constraints, such as skipping emulation-prevention
   // bytes and stop bits. See spec for more details.
-  // TODO(posciak): need separate unittests for this class.
   class H264BitReader {
    public:
     H264BitReader();