Add canExceedIdleDeadlineIfRequired function to Scheduler and use it in Oilpan

Source/platform/scheduler/Scheduler.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 Scheduler_h
 #define Scheduler_h
 
 #include "platform/PlatformExport.h"
 #include "public/platform/WebThread.h"
 #include "wtf/Functional.h"
@@ skipping 28 matching lines @@
     // For tasks related to loading, e.g. HTML parsing.  Loading tasks usually have default priority
     // but they may be deprioritized when the user is interacting with the device.
     // Takes ownership of |WebThread::Task|.
     void postLoadingTask(const WebTraceLocation&, WebThread::Task*);
 
     // Returns true if there is high priority work pending on the main thread
     // and the caller should yield to let the scheduler service that work.
     // Must be called on the main thread.
     bool shouldYieldForHighPriorityWork() const;
 
+    // Returns true if a currently running idle task could exceed its deadline
+    // without impacting user experience too much. This should only be used if
+    // there is a task which cannot be pre-empted and is likely to take longer
+    // than the largest expected idle task deadline. It should NOT be polled to
+    // check whether more work can be performed on the current idle task after
+    // its deadline has expired - post a new idle task for the continuation of
+    // the work in this case.
+    // Must be called from the main thread.
+    bool canExceedIdleDeadlineIfRequired() const;
+
 protected:
     Scheduler(WebScheduler*);
     virtual ~Scheduler();
 
     static Scheduler* s_sharedScheduler;
     WebScheduler* m_webScheduler;
 };
 
 } // namespace blink
 
 #endif // Scheduler_h