[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 "core/dom/ExecutionContext.h"
+#include "core/dom/ExecutionContextTask.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 NotifyTimezoneChange(ExecutionContext* context) {
+  v8::Isolate* isolate = toIsolate(context);
+  if (!isolate)

[haraken, 2016/10/17 03:59:49]

This shouldn't happen.

[leonhsl(Using Gerrit), 2016/10/17 07:30:01]

Got it, changed to DCHECK(isolate).

+    return;
+  v8::Date::DateTimeConfigurationChangeNotification(isolate);
+}
+
+}  // namespace
+
+// static
+void TimeZoneMonitorClient::Init() {
+  static TimeZoneMonitorClient* instance = nullptr;
+  if (!instance)
+    instance = new TimeZoneMonitorClient();
+}
+
+TimeZoneMonitorClient::TimeZoneMonitorClient() : m_binding(this) {
+  device::mojom::blink::TimeZoneMonitorPtr monitor;
+  Platform::current()->interfaceProvider()->getInterface(
+      mojo::GetProxy(&monitor));
+  monitor->AddClient(m_binding.CreateInterfacePtrAndBind());
+}
+
+TimeZoneMonitorClient::~TimeZoneMonitorClient() {}
+
+void TimeZoneMonitorClient::OnTimeZoneChange(const WTF::String& timeZoneInfo) {

[nhiroki, 2016/10/13 10:24:12]

Is this called only from the main thread?

I'm concerned that posting a task to all worker threads from non-main thread may
cause race conditions with worker thread destruction that happens on the main
thread.

[leonhsl(Using Gerrit), 2016/10/14 03:12:00]

Yeah mojo binding is thread hostile and the mojo methods are always called on
the thread on which the mojo impl has been bound. We bind our
TimeZoneMonitorClient impl at line#41 of this file, which executes on the main
thread.

[nhiroki, 2016/10/17 03:56:37]

OK, then we can safely access WorkerThread::workerThreads() from here (see my
other comments on WorkerThread.cpp).

[leonhsl(Using Gerrit), 2016/10/17 07:30:01]

Got it.

+  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;
+  }
+
+  NotifyTimezoneChange(nullptr);

[nhiroki, 2016/10/13 10:24:12]

Does this call make sense?

[leonhsl(Using Gerrit), 2016/10/14 03:12:00]

This is to notify the V8 isolate for current thread(main thread), I noticed that
toIsolate(nullptr) will lead to the isolate of current thread. Do you have any
suggestion here? Thanks.

[nhiroki, 2016/10/17 03:56:37]

Thank you for the explanation. I don't know whether there is a better way.
haraken@ may know it.

[haraken, 2016/10/17 03:59:49]

Can you make NotifyTimezoneChange take an Isolate parameter and then pass in
mainThreadIsolate()?

[leonhsl(Using Gerrit), 2016/10/17 07:30:01]

Done and thanks!

+  WorkerThread::PostTaskToAllWorkerThreads(
+      BLINK_FROM_HERE, createCrossThreadTask(&NotifyTimezoneChange));
+}
+
+}  // namespace blink