compositor worker: Use a WebThread for the compositor thread.

content/child/blink_platform_impl.cc

Index: content/child/blink_platform_impl.cc
diff --git a/content/child/blink_platform_impl.cc b/content/child/blink_platform_impl.cc
index 05d0cd2c903ba72e3f13cf6f13f3e2270c513c8a..75ac1489d92152578b6eb70a33921fcf3ad52010 100644
--- a/content/child/blink_platform_impl.cc
+++ b/content/child/blink_platform_impl.cc
@@ -83,11 +83,27 @@ using blink::WebThemeEngine;
 using blink::WebURL;
 using blink::WebURLError;
 using blink::WebURLLoader;
+using scheduler::WebThreadImplForWorkerScheduler;
 
 namespace content {
 
 namespace {
 
+class WebThreadForCompositor : public WebThreadImplForWorkerScheduler {
+ public:
+  explicit WebThreadForCompositor(base::Thread::Options options)
+      : WebThreadImplForWorkerScheduler("Compositor", options) {
+    Init();
+  }
+  ~WebThreadForCompositor() override {}
+
+ private:
+  // WebThreadImplForWorkerScheduler:
+  bool UseThreadTaskRunnerAsDefault() const override { return true; }
+
+  DISALLOW_COPY_AND_ASSIGN(WebThreadForCompositor);
+};
+
 class WebWaitableEventImpl : public blink::WebWaitableEvent {
  public:
   WebWaitableEventImpl(ResetPolicy policy, InitialState state) {
@@ -482,6 +498,16 @@ void BlinkPlatformImpl::InternalInit() {
   }
 }
 
+void BlinkPlatformImpl::WaitUntilWebThreadTLSUpdate(
+    scheduler::WebThreadBase* thread) {
+  base::WaitableEvent event(false, false);
+  thread->TaskRunner()->PostTask(
+      FROM_HERE,
+      base::Bind(&BlinkPlatformImpl::UpdateWebThreadTLS, base::Unretained(this),
+                 base::Unretained(thread), base::Unretained(&event)));
+  event.Wait();
+}
+
 void BlinkPlatformImpl::UpdateWebThreadTLS(blink::WebThread* thread,
                                            base::WaitableEvent* event) {
   DCHECK(!current_thread_slot_.Get());
@@ -557,15 +583,22 @@ blink::WebThread* BlinkPlatformImpl::createThread(const char* name) {
 scoped_ptr<scheduler::WebThreadBase> BlinkPlatformImpl::createThreadWithOptions(
     const char* name,
     base::Thread::Options options) {
-  scoped_ptr<scheduler::WebThreadBase> thread(
-      new scheduler::WebThreadImplForWorkerScheduler(name, options));
-  base::WaitableEvent event(false, false);
-  thread->TaskRunner()->PostTask(
-      FROM_HERE,
-      base::Bind(&BlinkPlatformImpl::UpdateWebThreadTLS, base::Unretained(this),
-                 base::Unretained(thread.get()), base::Unretained(&event)));
-  event.Wait();
-  return thread;
+  WebThreadImplForWorkerScheduler* thread =
+      new WebThreadImplForWorkerScheduler(name, options);
+  thread->Init();
+  WaitUntilWebThreadTLSUpdate(thread);
+  return make_scoped_ptr(thread);
+}
+
+scoped_ptr<scheduler::WebThreadBase>
+BlinkPlatformImpl::createCompositorThread() {
+  base::Thread::Options options;
+#if defined(OS_ANDROID)
+  options.priority = base::ThreadPriority::DISPLAY;
+#endif
+  compositor_thread_ = new WebThreadForCompositor(options);
+  WaitUntilWebThreadTLSUpdate(compositor_thread_);
+  return make_scoped_ptr(compositor_thread_);
 }
 
 blink::WebThread* BlinkPlatformImpl::currentThread() {