Create manager to track OffscreenCanvasSurfaceImpl instances

content/browser/renderer_host/offscreen_canvas_surface_manager.cc

+// 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 "base/lazy_instance.h"
+#include "content/browser/renderer_host/offscreen_canvas_surface_manager.h"
+
+namespace content {
+
+namespace {
+base::LazyInstance<OffscreenCanvasSurfaceManager> g_manager =

[dcheng, 2016/11/15 07:28:29]

Nit: let's make this a Leaky LazyInstance unless we have a reason to do
otherwise.

[xlai (Olivia), 2016/11/15 17:16:18]

Done.

+    LAZY_INSTANCE_INITIALIZER;
+}
+
+OffscreenCanvasSurfaceManager::OffscreenCanvasSurfaceManager() {}
+
+OffscreenCanvasSurfaceManager::~OffscreenCanvasSurfaceManager() {
+  registered_surface_instances_.clear();
+}
+
+OffscreenCanvasSurfaceManager* OffscreenCanvasSurfaceManager::GetInstance() {
+  return g_manager.Pointer();
+}
+
+void OffscreenCanvasSurfaceManager::RegisterOffscreenCanvasSurfaceInstance(
+    cc::FrameSinkId frame_sink_id,
+    OffscreenCanvasSurfaceImpl* surface_instance) {
+  DCHECK(surface_instance);
+  DCHECK_EQ(registered_surface_instances_.count(frame_sink_id), 0u);
+  registered_surface_instances_[frame_sink_id] = surface_instance->GetWeakPtr();
+}
+
+void OffscreenCanvasSurfaceManager::UnregisterOffscreenCanvasSurfaceInstance(
+    cc::FrameSinkId frame_sink_id) {
+  DCHECK_EQ(registered_surface_instances_.count(frame_sink_id), 1u);
+  registered_surface_instances_.erase(frame_sink_id);
+}
+
+OffscreenCanvasSurfaceImpl* OffscreenCanvasSurfaceManager::GetSurfaceInstance(
+    cc::FrameSinkId frame_sink_id) {
+  auto search = registered_surface_instances_.find(frame_sink_id);
+  if (search != registered_surface_instances_.end()) {
+    return search->second.get();
+  }
+  return nullptr;
+}
+
+}  // namespace content