[TimeZoneMonitor] Decouple renderer side impl from content to blink.

third_party/WebKit/Source/web/WebKit.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 64 matching lines @@
   return *initializer;
 }
 
 void initialize(Platform* platform) {
   Platform::initialize(platform);
 
   V8Initializer::initializeMainThread();
 
   modulesInitializer().initialize();
 
+  if (Platform::isMessageLoopReady())

[blundell, 2016/10/18 12:32:11]

I see, this is why you have initializeMojo() be safe for multiple calls. Did you
do this so that production code continues to Just Work? If so, maybe it makes
sense to rename the public-facing method initializeMojoForTesting() to make it
clear that it should only need to be called in a testing context where
blink::initialize() is called without the platform having a current thread?

[blundell, 2016/10/18 12:32:11]

Nit: It seems like you don't need to add Platform::isMessageLoopReady() because
you can just use if (platform->currentThread()) as is done on line 89 below.

[leonhsl(Using Gerrit), 2016/10/18 14:34:48]

Acknowledged.

[leonhsl(Using Gerrit), 2016/10/18 14:34:48]

I tried (platform->currentThread()) before, and turned out that it does not
really indicate the existence of a message loop for current thread. I also tried
to plumbed down into its implementation but did not find any hints leading to
base::MessageLoop::current(). Maybe haraken@ could help to comment about this.
Thanks.

[haraken, 2016/10/18 19:39:11]

I think Platform::currentThread() should work. Would you investigate a bit more
why it doesn't work?

[leonhsl(Using Gerrit), 2016/10/19 08:47:23]

content::TestBlinkWebUnitTestSupport is an impl of blink::Platform, and its
constructor will create the 'current thread' at [1], before calling
blink::initialize(), while at this time point there may has no message loop
ready, many test case codes will create their own type of message loop at a very
late stage.
[1]
https://cs.chromium.org/chromium/src/content/test/test_blink_web_unit_test_su...

+    initializeMojo();
+
   // currentThread is null if we are running on a thread without a message loop.
   if (WebThread* currentThread = platform->currentThread()) {
     DCHECK(!s_endOfTaskRunner);
     s_endOfTaskRunner = new EndOfTaskRunner;
     currentThread->addTaskObserver(s_endOfTaskRunner);
   }
 }
 
+void initializeMojo() {
+  modulesInitializer().initializeMojo();
+}
+
 void shutdown() {
   ThreadState::current()->cleanupMainThread();
 
   // currentThread() is null if we are running on a thread without a message
   // loop.
   if (WebThread* currentThread = Platform::current()->currentThread()) {
     currentThread->removeTaskObserver(s_endOfTaskRunner);
     s_endOfTaskRunner = nullptr;
   }
 
@@ skipping 51 matching lines @@
 void MemoryPressureNotificationToWorkerThreadIsolates(
     v8::MemoryPressureLevel level) {
   WorkerBackingThread::MemoryPressureNotificationToWorkerThreadIsolates(level);
 }
 
 void setRAILModeOnWorkerThreadIsolates(v8::RAILMode railMode) {
   WorkerBackingThread::setRAILModeOnWorkerThreadIsolates(railMode);
 }
 
 }  // namespace blink