Mojoify time zone update IPC from browser to renderer

content/browser/renderer_host/render_process_host_impl.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Represents the browser side of the browser <--> renderer communication
 // channel. There will be one RenderProcessHost per renderer process.
 
 #include "content/browser/renderer_host/render_process_host_impl.h"
 
 #include <algorithm>
@@ skipping 102 matching lines @@
 #include "content/browser/renderer_host/render_widget_host_impl.h"
 #include "content/browser/renderer_host/text_input_client_message_filter.h"
 #include "content/browser/resolve_proxy_msg_helper.h"
 #include "content/browser/service_worker/service_worker_context_wrapper.h"
 #include "content/browser/service_worker/service_worker_dispatcher_host.h"
 #include "content/browser/shared_worker/shared_worker_message_filter.h"
 #include "content/browser/shared_worker/worker_storage_partition.h"
 #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"
 #include "content/common/child_process_host_impl.h"
 #include "content/common/child_process_messages.h"
 #include "content/common/content_switches_internal.h"
 #include "content/common/frame_messages.h"
 #include "content/common/gpu_host_messages.h"
 #include "content/common/in_process_child_thread_params.h"
 #include "content/common/mojo/constants.h"
@@ skipping 1095 matching lines @@
   AddUIThreadInterface(
       registry.get(),
       base::Bind(&BroadcastChannelProvider::Connect,
                  base::Unretained(
                      storage_partition_impl_->GetBroadcastChannelProvider())));
   if (memory_coordinator::IsEnabled()) {
     AddUIThreadInterface(
         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),
                          file_task_runner);
 #if defined(USE_MINIKIN_HYPHENATION)
   registry->AddInterface(base::Bind(&hyphenation::HyphenationImpl::Create),
                          file_task_runner);
 #endif
 
   // These callbacks will be run immediately on the IO thread.
@@ skipping 34 matching lines @@
 
 int RenderProcessHostImpl::GetNextRoutingID() {
   return widget_helper_->GetNextRoutingID();
 }
 
 void RenderProcessHostImpl::ResumeDeferredNavigation(
     const GlobalRequestID& request_id) {
   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();
 }
 
 std::unique_ptr<base::SharedPersistentMemoryAllocator>
 RenderProcessHostImpl::TakeMetricsAllocator() {
   return std::move(metrics_allocator_);
 }
 
 const base::TimeTicks& RenderProcessHostImpl::GetInitTimeForNavigationMetrics()
@@ skipping 1628 matching lines @@
   LOG(ERROR) << "Terminating render process for bad Mojo message: " << error;
 
   // The ReceivedBadMessage call below will trigger a DumpWithoutCrashing. Alias
   // enough information here so that we can determine what the bad message was.
   base::debug::Alias(&error);
   bad_message::ReceivedBadMessage(process.get(),
                                   bad_message::RPH_MOJO_PROCESS_ERROR);
 }
 
 }  // namespace content