Introduce a basic Blink Scheduler

Source/platform/scheduler/Scheduler.cpp

+// Copyright 2014 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 "config.h"
+#include "platform/scheduler/Scheduler.h"
+
+#include "platform/Task.h"
+#include "platform/TraceEvent.h"
+#include "public/platform/Platform.h"
+
+namespace WebCore {
+
+namespace {
+
+class MainThreadTaskAdapter : public blink::WebThread::Task {
+public:
+    explicit MainThreadTaskAdapter(const Scheduler::Task& task)
+        : m_task(task)
+    {
+    }
+
+    // WebThread::Task implementation.
+    virtual void run() OVERRIDE
+    {
+        TRACE_EVENT0("blink", "MainThreadTaskAdapter::run");
+        m_task();
+    }
+
+private:
+    Scheduler::Task m_task;
+};
+
+}
+
+Scheduler* Scheduler::s_sharedScheduler = nullptr;
+
+void Scheduler::initializeOnMainThread()
+{
+    s_sharedScheduler = new Scheduler();
+}
+
+void Scheduler::shutdown()
+{
+    delete s_sharedScheduler;
+    s_sharedScheduler = nullptr;
+}
+
+Scheduler* Scheduler::shared()
+{
+    return s_sharedScheduler;
+}
+
+Scheduler::Scheduler()
+    : m_mainThread(blink::Platform::current()->currentThread())
+    , m_sharedTimerFunction(nullptr)
+{
+}
+
+Scheduler::~Scheduler()
+{
+}
+
+void Scheduler::scheduleTask(const Task& task)
+{
+    m_mainThread->postTask(new MainThreadTaskAdapter(task));
+}
+
+void Scheduler::postTask(const Task& task)
+{
+    scheduleTask(task);
+}
+
+void Scheduler::postInputTask(const Task& task)
+{
+    scheduleTask(task);
+}
+
+void Scheduler::postCompositorTask(const Task& task)
+{
+    scheduleTask(task);
+}
+
+void Scheduler::tickSharedTimer()
+{
+    TRACE_EVENT0("blink", "Scheduler::tickSharedTimer");
+    m_sharedTimerFunction();
+}
+
+void Scheduler::sharedTimerAdapter()
+{
+    shared()->tickSharedTimer();
+}
+
+void Scheduler::setSharedTimerFiredFunction(void (*function)())
+{
+    m_sharedTimerFunction = function;
+    blink::Platform::current()->setSharedTimerFiredFunction(function ? &Scheduler::sharedTimerAdapter : nullptr);
+}
+
+void Scheduler::setSharedTimerFireInterval(double interval)
+{
+    blink::Platform::current()->setSharedTimerFireInterval(interval);
+}
+
+void Scheduler::stopSharedTimer()
+{
+    blink::Platform::current()->stopSharedTimer();
+}
+
+bool Scheduler::shouldYieldForHighPriorityWork()
+{
+    return false;
+}
+
+} // namespace WebCore