[cc] facilitate use of BeginFrameAcks in tests.

cc/test/begin_frame_args_test.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_TEST_BEGIN_FRAME_ARGS_TEST_H_
 #define CC_TEST_BEGIN_FRAME_ARGS_TEST_H_
 
 #include <stdint.h>
 
 #include <iosfwd>
@@ skipping 44 matching lines @@
 
 // Allow "EXPECT_EQ(args1, args2);"
 // We don't define operator!= because EXPECT_NE(args1, args2) isn't all that
 // sensible.
 bool operator==(const BeginFrameArgs& lhs, const BeginFrameArgs& rhs);
 
 // Allow gtest to pretty print begin frame args.
 ::std::ostream& operator<<(::std::ostream& os, const BeginFrameArgs& args);
 void PrintTo(const BeginFrameArgs& args, ::std::ostream* os);
 
+// Allow "EXPECT_EQ(ack1, ack2);"
+bool operator==(const BeginFrameAck& lhs, const BeginFrameAck& rhs);
+
+// Allow gtest to pretty print BeginFrameAcks.
+::std::ostream& operator<<(::std::ostream& os, const BeginFrameAck& ack);
+void PrintTo(const BeginFrameAck& ack, ::std::ostream* os);
+
 }  // namespace cc
 
 #endif  // CC_TEST_BEGIN_FRAME_ARGS_TEST_H_