Add stream operator for SurfaceId/FrameSinkId/LocalFrameId.

cc/surfaces/surface_id.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_SURFACES_SURFACE_ID_H_
 #define CC_SURFACES_SURFACE_ID_H_
 
-#include <stddef.h>
 #include <stdint.h>
 
-#include <functional>
+#include <iosfwd>
 #include <string>
 
 #include "base/format_macros.h"
 #include "base/hash.h"
-#include "base/strings/stringprintf.h"
 #include "cc/surfaces/frame_sink_id.h"
 #include "cc/surfaces/local_frame_id.h"
 
 namespace cc {
 
 class SurfaceId {
  public:
   constexpr SurfaceId() = default;
 
   constexpr SurfaceId(const SurfaceId& other) = default;
@@ skipping 15 matching lines @@
 
   size_t hash() const {
     return base::HashInts(static_cast<uint64_t>(frame_sink_id_.hash()),
                           static_cast<uint64_t>(local_frame_id_.hash()));
   }
 
   const FrameSinkId& frame_sink_id() const { return frame_sink_id_; }
 
   const LocalFrameId& local_frame_id() const { return local_frame_id_; }
 
-  std::string ToString() const {
-    return base::StringPrintf("SurfaceId(%s, %s)",
-                              frame_sink_id_.ToString().c_str(),
-                              local_frame_id_.ToString().c_str());
-  }
+  std::string ToString() const;
 
   bool operator==(const SurfaceId& other) const {
     return frame_sink_id_ == other.frame_sink_id_ &&
            local_frame_id_ == other.local_frame_id_;
   }
 
   bool operator!=(const SurfaceId& other) const { return !(*this == other); }
 
   bool operator<(const SurfaceId& other) const {
     return std::tie(frame_sink_id_, local_frame_id_) <
            std::tie(other.frame_sink_id_, other.local_frame_id_);
   }
 
  private:
   // See SurfaceIdAllocator::GenerateId.
   FrameSinkId frame_sink_id_;
   LocalFrameId local_frame_id_;
 };
 
+std::ostream& operator<<(std::ostream& out, const SurfaceId& surface_id);
+
 struct SurfaceIdHash {
   size_t operator()(const SurfaceId& key) const { return key.hash(); }
 };
 
 }  // namespace cc
 
 #endif  // CC_SURFACES_SURFACE_ID_H_