mojo: Use TYPE_DEFAULT message-loop for browser-tests.

Use TYPE_DEFAULT message-loop for browser-tests, since that's what
mojo_runner uses by default. We would normally use TYPE_DEFAULT
message-loops for chrome --mash too, but keep using TYPE_UI for now,
since mojo:ui needs that, and it is not known whether mojo:ui will be
run at the type of the message-loop creation.

Also, remove references to MessagePumpMojo since that has been removed.

BUG=none
TBR=jam@ for base/threading/

Review-Url: https://codereview.chromium.org/2351603002
Cr-Commit-Position: refs/heads/master@{#419486}

base/threading/thread_restrictions.h

@@ -54,9 +54,6 @@ namespace gpu {
 class GpuChannelHost;
 }
 namespace mojo {
-namespace common {
-class MessagePumpMojo;
-}
 class SyncCallRestrictions;
 }
 namespace ui {
@@ -208,7 +205,6 @@ class BASE_EXPORT ThreadRestrictions {
   friend class ThreadTestHelper;
   friend class PlatformThread;
   friend class android::JavaHandlerThread;
-  friend class mojo::common::MessagePumpMojo;
   friend class mojo::SyncCallRestrictions;
   friend class ui::CommandBufferClientImpl;
   friend class ui::CommandBufferLocal;

chrome/app/mash/mash_runner.cc

@@ -126,7 +126,10 @@ void MashRunner::RunChild() {
 
 void MashRunner::StartChildApp(
     shell::mojom::ServiceRequest service_request) {
-  // TODO(sky): use MessagePumpMojo.
+  // TODO(sad): Normally, this would be a TYPE_DEFAULT message loop. However,
+  // TYPE_UI is needed for mojo:ui. But it is not known whether the child app is
+  // going to be mojo:ui at this point. So always create a TYPE_UI message loop
+  // for now.
   base::MessageLoop message_loop(base::MessageLoop::TYPE_UI);
   service_.reset(new mash::MashPackagedService);
   service_->set_context(base::MakeUnique<shell::ServiceContext>(
@@ -148,7 +151,6 @@ int MashMain() {
                        true,   // Timestamp
                        true);  // Tick count
 
-  // TODO(sky): use MessagePumpMojo.
   std::unique_ptr<base::MessageLoop> message_loop;
 #if defined(OS_LINUX)
   base::AtExitManager exit_manager;

chrome/test/base/mash_browser_tests_main.cc

@@ -121,7 +121,7 @@ std::unique_ptr<content::MojoShellConnection> CreateMojoShellConnection(
 }
 
 void StartChildApp(shell::mojom::ServiceRequest service_request) {
-  base::MessageLoop message_loop(base::MessageLoop::TYPE_UI);
+  base::MessageLoop message_loop(base::MessageLoop::TYPE_DEFAULT);
   base::RunLoop run_loop;
   mash::MashPackagedService service;
   std::unique_ptr<shell::ServiceContext> context =

services/shell/public/cpp/service_runner.h

@@ -61,8 +61,7 @@ class ServiceRunner {
  private:
   std::unique_ptr<Service> service_;
 
-  // MessageLoop type. TYPE_CUSTOM is default (MessagePumpMojo will be used as
-  // the underlying message pump).
+  // MessageLoop type. Default is TYPE_DEFAULT.
   base::MessageLoop::Type message_loop_type_;
   // Whether Run() has been called.
   bool has_run_;