Fix data race in RenderThreadImplBrowserTest

Use ThreadTaskRunnerHandle instead of BrowserThread::GetTaskRunnerForThread.
This avoids a data race in shutdown due to the fact that RendererScheduler
(used on a BrowserThread in this test) tramples the MessageLoop's TaskRunner
in a manner BrowserThreadImpl's TaskRunner facade does not anticipate.

Also opportunistically corrects some non-const ref arguments in
RenderThreadImpl.

BUG=672812

Review-Url: https://codereview.chromium.org/2568543002
Cr-Commit-Position: refs/heads/master@{#437755}

content/renderer/render_thread_impl.cc

@@ -600,7 +600,7 @@ void RenderThreadImpl::SetRenderMessageFilterForTesting(
 RenderThreadImpl::RenderThreadImpl(
     const InProcessChildThreadParams& params,
     std::unique_ptr<blink::scheduler::RendererScheduler> scheduler,
-    scoped_refptr<base::SingleThreadTaskRunner>& resource_task_queue)
+    const scoped_refptr<base::SingleThreadTaskRunner>& resource_task_queue)
     : ChildThreadImpl(Options::Builder()
                           .InBrowserProcess(params)
                           .AutoStartServiceManagerConnection(false)
@@ -636,7 +636,7 @@ RenderThreadImpl::RenderThreadImpl(
 }
 
 void RenderThreadImpl::Init(
-    scoped_refptr<base::SingleThreadTaskRunner>& resource_task_queue) {
+    const scoped_refptr<base::SingleThreadTaskRunner>& resource_task_queue) {
   TRACE_EVENT0("startup", "RenderThreadImpl::Init");
 
   base::trace_event::TraceLog::GetInstance()->SetThreadSortIndex(
@@ -1231,7 +1231,7 @@ void RenderThreadImpl::InitializeCompositorThread() {
 }
 
 void RenderThreadImpl::InitializeWebKit(
-    scoped_refptr<base::SingleThreadTaskRunner>& resource_task_queue) {
+    const scoped_refptr<base::SingleThreadTaskRunner>& resource_task_queue) {
   DCHECK(!blink_platform_impl_);
 
   const base::CommandLine& command_line =

content/renderer/render_thread_impl.h

@@ -486,7 +486,7 @@ class CONTENT_EXPORT RenderThreadImpl
   RenderThreadImpl(
       const InProcessChildThreadParams& params,
       std::unique_ptr<blink::scheduler::RendererScheduler> scheduler,
-      scoped_refptr<base::SingleThreadTaskRunner>& resource_task_queue);
+      const scoped_refptr<base::SingleThreadTaskRunner>& resource_task_queue);
   RenderThreadImpl(
       std::unique_ptr<base::MessageLoop> main_message_loop,
       std::unique_ptr<blink::scheduler::RendererScheduler> scheduler);
@@ -517,12 +517,13 @@ class CONTENT_EXPORT RenderThreadImpl
 
   void ClearMemory();
 
-  void Init(scoped_refptr<base::SingleThreadTaskRunner>& resource_task_queue);
+  void Init(
+      const scoped_refptr<base::SingleThreadTaskRunner>& resource_task_queue);
 
   void InitializeCompositorThread();
 
   void InitializeWebKit(
-      scoped_refptr<base::SingleThreadTaskRunner>& resource_task_queue);
+      const scoped_refptr<base::SingleThreadTaskRunner>& resource_task_queue);
 
   void OnTransferBitmap(const SkBitmap& bitmap, int resource_id);
   void OnGetAccessibilityTree();

content/renderer/render_thread_impl_browsertest.cc

@@ -127,13 +127,6 @@ class RenderThreadImplForTest : public RenderThreadImpl {
   ~RenderThreadImplForTest() override {}
 };
 
-class DummyListener : public IPC::Listener {
- public:
-  ~DummyListener() override {}
-
-  bool OnMessageReceived(const IPC::Message& message) override { return true; }
-};
-
 #if defined(COMPILER_MSVC)
 #pragma warning(pop)
 #endif
@@ -181,7 +174,7 @@ class RenderThreadImplBrowserTest : public testing::Test {
     browser_threads_.reset(
         new TestBrowserThreadBundle(TestBrowserThreadBundle::IO_MAINLOOP));
     scoped_refptr<base::SingleThreadTaskRunner> io_task_runner =
-        BrowserThread::GetTaskRunnerForThread(BrowserThread::IO);
+        base::ThreadTaskRunnerHandle::Get();
 
     InitializeMojo();
     ipc_support_.reset(new mojo::edk::test::ScopedIPCSupport(io_task_runner));
@@ -195,11 +188,10 @@ class RenderThreadImplBrowserTest : public testing::Test {
     IPC::mojom::ChannelBootstrapPtr channel_bootstrap;
     child_connection_->GetRemoteInterfaces()->GetInterface(&channel_bootstrap);
 
-    dummy_listener_.reset(new DummyListener);
     channel_ = IPC::ChannelProxy::Create(
         IPC::ChannelMojo::CreateServerFactory(
             channel_bootstrap.PassInterface().PassHandle(), io_task_runner),
-        dummy_listener_.get(), io_task_runner);
+        nullptr, io_task_runner);
 
     mock_process_.reset(new MockRenderProcess);
     test_task_counter_ = make_scoped_refptr(new TestTaskCounter());
@@ -239,7 +231,6 @@ class RenderThreadImplBrowserTest : public testing::Test {
   std::unique_ptr<mojo::edk::test::ScopedIPCSupport> ipc_support_;
   std::unique_ptr<TestServiceManagerContext> shell_context_;
   std::unique_ptr<ChildConnection> child_connection_;
-  std::unique_ptr<DummyListener> dummy_listener_;
   std::unique_ptr<IPC::ChannelProxy> channel_;
 
   std::unique_ptr<MockRenderProcess> mock_process_;