Add stream operator for SurfaceId/FrameSinkId/LocalFrameId.

cc/surfaces/frame_sink_id.cc

Index: cc/surfaces/frame_sink_id.cc
diff --git a/cc/surfaces/frame_sink_id.cc b/cc/surfaces/frame_sink_id.cc
new file mode 100644
index 0000000000000000000000000000000000000000..129c740ba7f2661816ca22c58eefca98e5d182e1
--- /dev/null
+++ b/cc/surfaces/frame_sink_id.cc
@@ -0,0 +1,19 @@
+// Copyright 2016 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.
+
+#include "cc/surfaces/frame_sink_id.h"
+
+#include "base/strings/stringprintf.h"
+
+namespace cc {
+
+std::string FrameSinkId::ToString() const {
+  return base::StringPrintf("FrameSinkId(%d, %d)", client_id_, sink_id_);
+}
+
+std::ostream& operator<<(std::ostream& out, const FrameSinkId& frame_sink_id) {
+  return out << frame_sink_id.ToString();
+}
+
+}  // namespace cc