Implement idle task scheduling.

Source/platform/scheduler/Scheduler.h

Index: Source/platform/scheduler/Scheduler.h
diff --git a/Source/platform/scheduler/Scheduler.h b/Source/platform/scheduler/Scheduler.h
index 7f7835abcf76d6ac90c6780e6fdad520e3808d80..86ab076cdbb4c1a4137e0ef59e245975a19ffacd 100644
--- a/Source/platform/scheduler/Scheduler.h
+++ b/Source/platform/scheduler/Scheduler.h
@@ -10,6 +10,7 @@
 #include "wtf/DoubleBufferedDeque.h"
 #include "wtf/Functional.h"
 #include "wtf/Noncopyable.h"
+#include "wtf/OwnPtr.h"
 #include "wtf/ThreadingPrimitives.h"
 
 namespace blink {
@@ -64,6 +65,7 @@ protected:
     class MainThreadPendingHighPriorityTaskRunner;
     friend class MainThreadPendingTaskRunner;
     friend class MainThreadPendingHighPriorityTaskRunner;
+    friend class TracedIdleTask;
 
     enum SchedulerPolicy {
         Normal,
@@ -73,8 +75,8 @@ protected:
     Scheduler();
     virtual ~Scheduler();
 
-    void scheduleIdleTask(const TraceLocation&, const IdleTask&);
     void postHighPriorityTaskInternal(const TraceLocation&, const Task&, const char* traceName);
+    void postIdleTaskInternal(const TraceLocation&, const IdleTask&, const char* traceName);
 
     static void sharedTimerAdapter();
 
@@ -89,7 +91,19 @@ protected:
     void swapQueuesRunPendingTasksAndAllowHighPriorityTaskRunnerPosting();
 
     // Returns true if any work was done.
-    bool executeHighPriorityTasks(Deque<TracedTask>&);
+    bool executeHighPriorityTasks(Deque<OwnPtr<TracedTask> >&);
+
+    // Returns true if any work was done.
+    bool swapQueuesAndRunPendingIdleTasks();
+
+    // Returns true if any work was done.
+    bool executeIdleTasks(Deque<OwnPtr<TracedTask> >&);
+
+    // Reposts all the tasks in idleTasks onto the idle task queue.
+    void repostAllIdleTasks(Deque<OwnPtr<TracedTask> >&);
+
+    // Returns the time in seconds until the current frame deadline expires.
+    double getSecondsUntilFrameDeadline() const;

[Sami, 2014/09/24 14:00:40]

nit: drop the |get|, it's cleaner

[rmcilroy, 2014/09/29 17:42:57]

Done.

 
     // Return the current SchedulerPolicy.
     SchedulerPolicy schedulerPolicy() const;
@@ -118,9 +132,12 @@ protected:
     // This mutex protects calls to the pending task queue, m_highPriorityTaskRunnerPosted and
     // m_compositorPriorityPolicyEndTimeSeconds.
     Mutex m_pendingTasksMutex;
-    DoubleBufferedDeque<TracedTask> m_pendingHighPriorityTasks;
+    DoubleBufferedDeque<OwnPtr<TracedTask> > m_pendingHighPriorityTasks;

[Sami, 2014/09/24 14:00:40]

As of Nico's email to chromium-dev@ yesterday I think we can now finally write
>> here :)

[rmcilroy, 2014/09/29 17:42:57]

Acknowledged.

+    DoubleBufferedDeque<OwnPtr<TracedTask> > m_pendingIdleTasks;
     double m_compositorPriorityPolicyEndTimeSeconds;
 
+    double m_currentFrameDeadlineSeconds;
+
     // Declared volatile as it is atomically incremented.
     volatile int m_highPriorityTaskCount;