Mojoify time zone update IPC from browser to renderer

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 7a225cf71b03d35c77ce75c3c717b481640fabee..a9dc9e47e09769afeaf176fd1055da1a4aae5ea9 100644
--- a/content/browser/renderer_host/render_process_host_impl.cc
+++ b/content/browser/renderer_host/render_process_host_impl.cc
@@ -120,6 +120,7 @@
 #include "content/browser/speech/speech_recognition_dispatcher_host.h"
 #include "content/browser/storage_partition_impl.h"
 #include "content/browser/streams/stream_context.h"
+#include "content/browser/time_zone_monitor.h"
 #include "content/browser/tracing/trace_message_filter.h"
 #include "content/browser/websockets/websocket_manager.h"
 #include "content/browser/webui/web_ui_controller_factory_registry.h"
@@ -1235,6 +1236,12 @@ void RenderProcessHostImpl::RegisterMojoInterfaces() {
         registry.get(), base::Bind(&CreateMemoryCoordinatorHandle, GetID()));
   }
 
+  AddUIThreadInterface(
+      registry.get(),
+      base::Bind(&TimeZoneMonitor::Bind,
+                 base::Unretained(
+                     BrowserMainLoop::GetInstance()->time_zone_monitor())));

[dcheng, 2016/09/06 22:20:38]

With some hand-waving, I can see how the use of base::Unretained() are safe
(they refer to members or |this|), but I'm not sure how this one is safe. What's
the relationship between RPH and BrowserMainLoop?

[blundell, 2016/09/07 14:40:05]

OK, I had to dig into this to respond to your question and validate my intuition
that this logically "should be" safe. It is unfortunately subtle:

BrowserMainLoop::ShutdownThreadsAndCleanUp() deletes its
mojo::edk::ScopedIPCSupport instance. The header comment on the latter says that
it "shuts down Mojo on destruction". So after the BrowserMainLoop is destroyed
(which is when its TimeZoneMonitor instance is deleted), there should not be any
incoming Mojo connection requests by design. Thoughts?

 

+
   scoped_refptr<base::SingleThreadTaskRunner> file_task_runner =
       BrowserThread::GetTaskRunnerForThread(BrowserThread::FILE);
   registry->AddInterface(base::Bind(&MimeRegistryImpl::Create),
@@ -1289,10 +1296,6 @@ void RenderProcessHostImpl::ResumeDeferredNavigation(
   widget_helper_->ResumeDeferredNavigation(request_id);
 }
 
-void RenderProcessHostImpl::NotifyTimezoneChange(const std::string& zone_id) {
-  Send(new ViewMsg_TimezoneChange(zone_id));
-}
-
 shell::InterfaceProvider* RenderProcessHostImpl::GetRemoteInterfaces() {
   return mojo_child_connection_->GetRemoteInterfaces();
 }