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

third_party/WebKit/Source/web/WebKit.cpp

Index: third_party/WebKit/Source/web/WebKit.cpp
diff --git a/third_party/WebKit/Source/web/WebKit.cpp b/third_party/WebKit/Source/web/WebKit.cpp
index f32df4dfb71b7c477d397c31330b30e5a1b087a8..fc88a2a83f405e52669be20614fda45b15600679 100644
--- a/third_party/WebKit/Source/web/WebKit.cpp
+++ b/third_party/WebKit/Source/web/WebKit.cpp
@@ -82,6 +82,9 @@ void initialize(Platform* platform) {
 
   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);
@@ -90,6 +93,10 @@ void initialize(Platform* platform) {
   }
 }
 
+void initializeMojo() {
+  modulesInitializer().initializeMojo();
+}
+
 void shutdown() {
   ThreadState::current()->cleanupMainThread();