Refactor TimeBase to post tasks. Workers to use real Idle tasks.

public/platform/WebScheduler.h

 // 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.
 
 #ifndef WebScheduler_h
 #define WebScheduler_h
 
 #include "WebCommon.h"
 #include "public/platform/WebThread.h"
 
@@ skipping 39 matching lines @@
     // task has run. This enables posting of a task which won't stop the Blink
     // main thread from sleeping, but will start running after it wakes up.
     // Takes ownership of |IdleTask|. Can be called from any thread.
     virtual void postIdleTaskAfterWakeup(const WebTraceLocation&, WebThread::IdleTask*) { }
 
     // Schedule a loading task to be run on the Blink main thread. Loading
     // tasks usually have the default priority, but may be deprioritised
     // when the user is interacting with the device.
     // Takes ownership of |WebThread::Task|. Can be called from any thread.
     virtual void postLoadingTask(const WebTraceLocation&, WebThread::Task*) { }
+
+    // Schedule a timer task to be run on the Blink main thread. Timer Tasks
+    // tasks usually have the default priority, but may be delayed
+    // when the user is interacting with the device.
+    // Takes ownership of |WebThread::Task|. Can be called from any thread.
+    virtual void postTimerTask(const WebTraceLocation&, WebThread::Task*, long long delayMs) { }
 };
 
 } // namespace blink
 
 #endif // WebScheduler_h