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

third_party/WebKit/Source/modules/time_zone_monitor/TimeZoneMonitorClient.cpp

+// Copyright 2016 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.
+
+#include "modules/time_zone_monitor/TimeZoneMonitorClient.h"
+
+#include "bindings/core/v8/V8Binding.h"
+#include "bindings/core/v8/V8PerIsolateData.h"
+#include "core/dom/ExecutionContext.h"
+#include "core/dom/ExecutionContextTask.h"
+#include "core/workers/WorkerBackingThread.h"
+#include "core/workers/WorkerThread.h"
+#include "public/platform/InterfaceProvider.h"
+#include "public/platform/Platform.h"
+#include "third_party/icu/source/i18n/unicode/timezone.h"
+#include <v8.h>
+
+namespace blink {
+
+namespace {
+
+// Notify V8 that the date/time configuration of the system might have changed.
+void NotifyTimezoneChangeToV8(v8::Isolate* isolate) {
+  DCHECK(isolate);
+  v8::Date::DateTimeConfigurationChangeNotification(isolate);
+}
+
+void NotifyTimezoneChangeOnWorkerThread(ExecutionContext* context) {
+  NotifyTimezoneChangeToV8(toIsolate(context));
+}
+
+}  // namespace
+
+// static
+TimeZoneMonitorClient& TimeZoneMonitorClient::Init() {

[haraken, 2016/10/26 11:21:59]

The return value is unused.

[leonhsl(Using Gerrit), 2016/10/26 11:45:48]

Just want to create it as long-live singleton, and no need to hold its reference
elsewhere. Any suggestion? 

[haraken, 2016/10/26 13:27:11]

Can you just change the return type to void?

[leonhsl(Using Gerrit), 2016/10/27 05:01:27]

Done.

+  DEFINE_STATIC_LOCAL(TimeZoneMonitorClient, instance, ());

[haraken, 2016/10/26 11:21:59]

Why do you need to use DEFINE_STATIC_LOCAL?

[leonhsl(Using Gerrit), 2016/10/26 11:45:48]

According your previous comment at:
https://codereview.chromium.org/2402983002/diff/180001/third_party/WebKit/Sou...
 Assuming it's better than bare 'static XXX* xxx;'

[haraken, 2016/10/26 13:27:11]

OK, you want to make it a singleton... Then DEFINE_STATIC_LOCAL makes sense.

+  return instance;
+}
+
+TimeZoneMonitorClient::TimeZoneMonitorClient() : m_binding(this) {
+  DCHECK(isMainThread());
+
+  device::mojom::blink::TimeZoneMonitorPtr monitor;
+  Platform::current()->interfaceProvider()->getInterface(

[haraken, 2016/10/26 12:02:12]

I begin to wonder why you need to run these steps when initializing Blink...
Other Mojo clients are calling AddClient later when the client gets actually
constructed.

Why does TimeZoneMonitorClient need to register itself to Mojo in the
initialization phase? In other words, why do you need to instantiate
TimeZoneMonitorClient so eagerly?

[leonhsl(Using Gerrit), 2016/10/26 12:13:00]

Because TimeZoneMonitorClient needs to be able to get time zone change
notifications from Browser, once Blink started. Originally AddClient() happened
in RenderThreadImpl::Init(), right after initializing Blink.
Maybe 'Other Mojo clients' constructions are triggered by javascript function
call or some other code logic.  

[haraken, 2016/10/26 13:27:11]

ok

+      mojo::GetProxy(&monitor));
+  monitor->AddClient(m_binding.CreateInterfacePtrAndBind());
+}
+
+TimeZoneMonitorClient::~TimeZoneMonitorClient() {}
+
+void TimeZoneMonitorClient::OnTimeZoneChange(const WTF::String& timeZoneInfo) {
+  DCHECK(isMainThread());
+
+  if (!timeZoneInfo.isEmpty()) {
+    icu::TimeZone* zone = icu::TimeZone::createTimeZone(
+        icu::UnicodeString::fromUTF8(timeZoneInfo.utf8().data()));
+    icu::TimeZone::adoptDefault(zone);
+    VLOG(1) << "ICU default timezone is set to " << timeZoneInfo;
+  }
+
+  NotifyTimezoneChangeToV8(V8PerIsolateData::mainThreadIsolate());
+
+  HashSet<WorkerThread*>& threads = WorkerThread::workerThreads();
+  HashSet<WorkerBackingThread*> posted;
+  for (WorkerThread* thread : threads) {
+    // Ensure every WorkerBackingThread(holding one platform thread) only get
+    // the task posted once, because one WorkerBackingThread could be shared
+    // among multiple WorkerThreads.
+    if (posted.contains(&thread->workerBackingThread()))
+      continue;
+    thread->postTask(BLINK_FROM_HERE, createCrossThreadTask(
+                                          &NotifyTimezoneChangeOnWorkerThread));
+    posted.add(&thread->workerBackingThread());
+  }
+}
+
+}  // namespace blink