Allow media track switching.

content/renderer/media/media_interface_provider.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 "content/renderer/media/media_interface_provider.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "media/mojo/interfaces/content_decryption_module.mojom.h"
 #include "media/mojo/interfaces/renderer.mojom.h"
 #include "mojo/public/cpp/bindings/interface_request.h"
 #include "services/service_manager/public/cpp/interface_provider.h"
 
 namespace content {
 
 MediaInterfaceProvider::MediaInterfaceProvider(
     service_manager::InterfaceProvider* remote_interfaces)
-    : remote_interfaces_(remote_interfaces) {}
+    : remote_interfaces_(remote_interfaces), weak_factory_(this) {
+  task_runner_ = base::ThreadTaskRunnerHandle::Get();
+  weak_this_ = weak_factory_.GetWeakPtr();
+}
 
 MediaInterfaceProvider::~MediaInterfaceProvider() {
   DCHECK(thread_checker_.CalledOnValidThread());
 }
 
 void MediaInterfaceProvider::GetInterface(const std::string& interface_name,
                                           mojo::ScopedMessagePipeHandle pipe) {
   DVLOG(1) << __func__;
+  if (!task_runner_->BelongsToCurrentThread()) {
+    task_runner_->PostTask(
+        FROM_HERE, base::Bind(&MediaInterfaceProvider::GetInterface, weak_this_,
+                              interface_name, base::Passed(&pipe)));
+    return;
+  }

[xhwang, 2017/03/27 19:13:53]

nit: empty line 

[servolk, 2017/03/27 22:34:12]

Done.

   DCHECK(thread_checker_.CalledOnValidThread());
 
   if (interface_name == media::mojom::ContentDecryptionModule::Name_) {
     GetMediaInterfaceFactory()->CreateCdm(
         mojo::MakeRequest<media::mojom::ContentDecryptionModule>(
             std::move(pipe)));
   } else if (interface_name == media::mojom::Renderer::Name_) {
     GetMediaInterfaceFactory()->CreateRenderer(
         std::string(),
         mojo::MakeRequest<media::mojom::Renderer>(std::move(pipe)));
@@ skipping 23 matching lines @@
 }
 
 void MediaInterfaceProvider::OnConnectionError() {
   DVLOG(1) << __func__;
   DCHECK(thread_checker_.CalledOnValidThread());
 
   media_interface_factory_.reset();
 }
 
 }  // namespace content