NOT FOR REVIEW: Adding prioritized incoming task queue to renderers

content/renderer/renderer_message_loop.cc

+// 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.
+
+#include "content/renderer/renderer_message_loop.h"
+
+#include "base/message_loop/high_priority_task_runner.h"
+#include "content/renderer/render_thread_impl.h"
+
+namespace content {
+
+RendererMessageLoop::RendererMessageLoop()
+    : normal_work_queue_deficit_(0) {
+  high_priority_task_runner_ = new base::HighPriorityTaskRunner(this);
+}
+
+RendererMessageLoop::RendererMessageLoop(scoped_ptr<base::MessagePump> pump)
+    : MessageLoop(pump.Pass()),
+      normal_work_queue_deficit_(0) {
+  high_priority_task_runner_ = new base::HighPriorityTaskRunner(this);
+}
+
+RendererMessageLoop::~RendererMessageLoop() {
+}
+
+void RendererMessageLoop::EnableHighPriorityIncomingTaskQueue() {
+  DCHECK(RenderThreadImpl::current());
+  DCHECK(!is_running());
+
+  RenderThreadImpl::current()->UseHighPriorityTaskRunner(
+      high_priority_task_runner_);
+}
+
+void RendererMessageLoop::ReloadWorkQueue() {
+  MessageLoop::ReloadWorkQueue();
+  if (high_priority_work_queue_.empty())
+    high_priority_task_runner_->ReloadWorkQueue(&high_priority_work_queue_);
+}
+
+base::TaskQueue& RendererMessageLoop::SelectNextWorkQueue() {
+  // TODO(bashi): Need to be tuned.
+  static const int kMaxDeficit = 1000;
+  if (!high_priority_work_queue_.empty() &&
+      normal_work_queue_deficit_ <= kMaxDeficit) {
+    ++normal_work_queue_deficit_;
+    return high_priority_work_queue_;
+  }
+
+  normal_work_queue_deficit_ = 0;
+  return MessageLoop::SelectNextWorkQueue();
+}
+
+}  // namespace content