Revert of Move content's shell connections to the IO thread

content/browser/renderer_host/render_process_host_impl.cc

Index: content/browser/renderer_host/render_process_host_impl.cc
diff --git a/content/browser/renderer_host/render_process_host_impl.cc b/content/browser/renderer_host/render_process_host_impl.cc
index c4b72a3241682e420e1aee06434c9c44cbaf6003..de830f42ef43f732fe58fdda9d5c94fe7df35ba9 100644
--- a/content/browser/renderer_host/render_process_host_impl.cc
+++ b/content/browser/renderer_host/render_process_host_impl.cc
@@ -169,8 +169,6 @@
 #include "mojo/edk/embedder/embedder.h"
 #include "net/url_request/url_request_context_getter.h"
 #include "ppapi/shared_impl/ppapi_switches.h"
-#include "services/shell/public/cpp/interface_provider.h"
-#include "services/shell/public/cpp/interface_registry.h"
 #include "services/shell/runner/common/switches.h"
 #include "storage/browser/fileapi/sandbox_file_system_backend.h"
 #include "third_party/skia/include/core/SkBitmap.h"
@@ -602,8 +600,6 @@
 #endif  // defined(OS_MACOSX)
 #endif  // USE_ATTACHMENT_BROKER
 
-  scoped_refptr<base::SequencedTaskRunner> io_task_runner =
-      BrowserThread::GetTaskRunnerForThread(BrowserThread::IO);
   shell::Connector* connector =
       BrowserContext::GetShellConnectorFor(browser_context_);
   // Some embedders may not initialize Mojo or the shell connector for a browser
@@ -616,14 +612,15 @@
     if (!MojoShellConnection::GetForProcess()) {
       shell::mojom::ServiceRequest request = mojo::GetProxy(&test_service_);
       MojoShellConnection::SetForProcess(MojoShellConnection::Create(
-          std::move(request), io_task_runner));
+          std::move(request)));
     }
     connector = MojoShellConnection::GetForProcess()->GetConnector();
   }
   mojo_child_connection_.reset(new MojoChildConnection(
       kRendererMojoApplicationName,
-      base::StringPrintf("%d_%d", id_, instance_id_++), child_token_, connector,
-      io_task_runner));
+      base::StringPrintf("%d_%d", id_, instance_id_++),
+      child_token_,
+      connector));
 }
 
 // static
@@ -763,7 +760,8 @@
     in_process_renderer_.reset(
         g_renderer_main_thread_factory(InProcessChildThreadParams(
             channel_id,
-            BrowserThread::GetTaskRunnerForThread(BrowserThread::IO),
+            BrowserThread::UnsafeGetMessageLoopForThread(BrowserThread::IO)
+                ->task_runner(),
             mojo_channel_token_,
             mojo_child_connection_->service_token())));
 
@@ -1123,11 +1121,16 @@
 }
 
 shell::InterfaceRegistry* RenderProcessHostImpl::GetInterfaceRegistry() {
-  return mojo_child_connection_->GetInterfaceRegistry();
+  return GetChildConnection()->GetInterfaceRegistry();
 }
 
 shell::InterfaceProvider* RenderProcessHostImpl::GetRemoteInterfaces() {
-  return mojo_child_connection_->GetRemoteInterfaces();
+  return GetChildConnection()->GetRemoteInterfaces();
+}
+
+shell::Connection* RenderProcessHostImpl::GetChildConnection() {
+  DCHECK(mojo_child_connection_);
+  return mojo_child_connection_->connection();
 }
 
 std::unique_ptr<base::SharedPersistentMemoryAllocator>
@@ -2431,8 +2434,9 @@
     connector = MojoShellConnection::GetForProcess()->GetConnector();
   mojo_child_connection_.reset(new MojoChildConnection(
       kRendererMojoApplicationName,
-      base::StringPrintf("%d_%d", id_, instance_id_++), child_token_, connector,
-      BrowserThread::GetTaskRunnerForThread(BrowserThread::IO)));
+      base::StringPrintf("%d_%d", id_, instance_id_++),
+      child_token_,
+      connector));
 
   within_process_died_observer_ = true;
   NotificationService::current()->Notify(