Adds ability to load services on background thread

And enables this for the native viewport. Currently the native
viewport implementation can end up synchronously waiting for
messages. This means if the viewmanager (which uses the native
viewport) and native viewport end up on the same thread they can
easily deadlock. For now I'm moving native viewport to its own
thread. Long term native viewport should live in its own process
(according to piman).

BUG=365012
TEST=none
R=davemoore@chromium.org

Review URL: https://codereview.chromium.org/263163005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@268471 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 16 insertions, 1 deletions

diff --git a/mojo/shell/context.cc b/mojo/shell/context.cc
index 86f06c3..f5d405f 100644
--- a/mojo/shell/context.cc
+++ b/mojo/shell/context.cc
@@ -11,6 +11,7 @@
 #include "mojo/embedder/embedder.h"
 #include "mojo/gles2/gles2_support_impl.h"
 #include "mojo/public/cpp/shell/application.h"
+#include "mojo/service_manager/background_service_loader.h"
 #include "mojo/service_manager/service_loader.h"
 #include "mojo/service_manager/service_manager.h"
 #include "mojo/services/native_viewport/native_viewport_service.h"
@@ -122,8 +123,14 @@ Context::Context()
   service_manager_.set_default_loader(
       scoped_ptr<ServiceLoader>(
           new DynamicServiceLoader(this, runner_factory.Pass())));
+  // The native viewport service synchronously waits for certain messages. If we
+  // don't run it on its own thread we can easily deadlock. Long term native
+  // viewport should run its own process so that this isn't an issue.
   service_manager_.SetLoaderForURL(
-      scoped_ptr<ServiceLoader>(new NativeViewportServiceLoader(this)),
+      scoped_ptr<ServiceLoader>(
+          new BackgroundServiceLoader(
+              scoped_ptr<ServiceLoader>(new NativeViewportServiceLoader(this)),
+              "native_viewport")),
       GURL("mojo:mojo_native_viewport_service"));
 #if defined(USE_AURA)
   // TODO(sky): need a better way to find this. It shouldn't be linked in.
@@ -145,6 +152,14 @@ Context::Context()
 }
 
 Context::~Context() {
+  // mojo_view_manager uses native_viewport. Destroy mojo_view_manager first so
+  // that there aren't shutdown ordering issues. Once native viewport service is
+  // moved into its own process this can likely be nuked.
+#if defined(USE_AURA)
+  service_manager_.SetLoaderForURL(
+      scoped_ptr<ServiceLoader>(),
+      GURL("mojo:mojo_view_manager"));
+#endif
   service_manager_.set_default_loader(scoped_ptr<ServiceLoader>());
 }