Add a Display and ContextProvider concept to mojom, use to recreate

services/surfaces/surfaces_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 MOJO_SERVICES_SURFACES_SURFACES_SCHEDULER_H_
 #define MOJO_SERVICES_SURFACES_SURFACES_SCHEDULER_H_
 
+#include <set>
+
 #include "cc/scheduler/scheduler.h"
 
+namespace cc {
+class Display;
+}
+
 namespace surfaces {
 
 class SurfacesScheduler : public cc::SchedulerClient {
  public:
-  class Client {
-   public:
-    virtual void Draw() = 0;
-
-   protected:
-    virtual ~Client();
-  };
-
-  explicit SurfacesScheduler(Client* client);
+  SurfacesScheduler();
   ~SurfacesScheduler();
 
   void SetNeedsDraw();
 
   void OnVSyncParametersUpdated(base::TimeTicks timebase,
                                 base::TimeDelta interval);
 
+  void AddDisplay(cc::Display* display);
+  void RemoveDisplay(cc::Display* display);
+
  private:
   void WillBeginImplFrame(const cc::BeginFrameArgs& args) override;
   void ScheduledActionSendBeginMainFrame() override;
   cc::DrawResult ScheduledActionDrawAndSwapIfPossible() override;
   cc::DrawResult ScheduledActionDrawAndSwapForced() override;
   void ScheduledActionAnimate() override;
   void ScheduledActionCommit() override;
   void ScheduledActionActivateSyncTree() override;
   void ScheduledActionBeginOutputSurfaceCreation() override;
   void ScheduledActionPrepareTiles() override;
   void DidAnticipatedDrawTimeChange(base::TimeTicks time) override;
   base::TimeDelta DrawDurationEstimate() override;
   base::TimeDelta BeginMainFrameToCommitDurationEstimate() override;
   base::TimeDelta CommitToActivateDurationEstimate() override;
   void DidBeginImplFrameDeadline() override;
   void SendBeginFramesToChildren(const cc::BeginFrameArgs& args) override;
   void SendBeginMainFrameNotExpectedSoon() override;
 
-  Client* client_;
+  std::set<cc::Display*> displays_;
   scoped_ptr<cc::Scheduler> scheduler_;
   base::TimeDelta draw_estimate_;
 
   DISALLOW_COPY_AND_ASSIGN(SurfacesScheduler);
 };
 
 }  // namespace mojo
 
 #endif  // MOJO_SERVICES_SURFACES_SURFACES_SCHEDULER_H_