Fix mojo startup

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 5ce5e599bde2418bc37fd530267810ddcb7cc4df..32246aed47381fb3799b434162a8c70e8c9ccdca 100644
--- a/content/browser/renderer_host/render_process_host_impl.cc
+++ b/content/browser/renderer_host/render_process_host_impl.cc
@@ -395,6 +395,7 @@ RenderProcessHostImpl::RenderProcessHostImpl(
       is_self_deleted_(false),
 #endif
       pending_views_(0),
+      mojo_activation_required_(false),
       visible_widgets_(0),
       backgrounded_(true),
       is_initialized_(false),
@@ -604,6 +605,20 @@ bool RenderProcessHostImpl::Init() {
   return true;
 }
 
+void RenderProcessHostImpl::MaybeActivateMojo() {
+  // TODO(darin): Following security review, we can unconditionally initialize
+  // Mojo in all renderers. We will then be able to directly call Activate()
+  // from OnProcessLaunched.
+  if (!mojo_activation_required_)
+    return;  // Waiting on someone to require Mojo.
+
+  if (!GetHandle())
+    return;  // Waiting on renderer startup.
+
+  if (!mojo_application_host_->did_activate())
+    mojo_application_host_->Activate(this, GetHandle());
+}
+
 void RenderProcessHostImpl::CreateMessageFilters() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   AddFilter(new ResourceSchedulerFilter(GetID()));
@@ -1972,13 +1987,10 @@ void RenderProcessHostImpl::OnProcessLaunched() {
       Source<RenderProcessHost>(this),
       NotificationService::NoDetails());
 
-  // TODO(darin): This is blocked on security review. Un-commenting this will
-  // allow Mojo calls from all renderers.
-#if 0
-  // Let the Mojo system get setup on the child process side before any other
-  // IPCs arrive. This way those may safely generate Mojo-related RPCs.
-  mojo_application_host_->Activate(this, GetHandle());
-#endif
+  // Allow Mojo to be setup before the renderer sees any Chrome IPC messages.
+  // This way, Mojo can be safely used from the renderer in response to any
+  // Chrome IPC message.
+  MaybeActivateMojo();
 
   while (!queued_messages_.empty()) {
     Send(queued_messages_.front());
@@ -2065,8 +2077,8 @@ void RenderProcessHostImpl::DecrementWorkerRefCount() {
 void RenderProcessHostImpl::ConnectTo(
     const base::StringPiece& service_name,
     mojo::ScopedMessagePipeHandle handle) {
-  if (!mojo_application_host_->did_activate())
-    mojo_application_host_->Activate(this, GetHandle());
+  mojo_activation_required_ = true;
+  MaybeActivateMojo();
 
   mojo::AllocationScope scope;
   mojo_application_host_->shell_client()->AcceptConnection(service_name,