Add a flag to flush the canvases during SkMultiPictureDraw::draw().

include/core/SkMultiPictureDraw.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkMultiPictureDraw_DEFINED
 #define SkMultiPictureDraw_DEFINED
 
@@ skipping 27 matching lines @@
      *  @param paint    if non-NULL, draw picture to a temporary buffer
      *                  and then apply the paint when the result is drawn
      */
     void add(SkCanvas* canvas,
              const SkPicture* picture,
              const SkMatrix* matrix = NULL,
              const SkPaint* paint = NULL);
 
     /**
      *  Perform all the previously added draws. This will reset the state
-     *  of this object.
+     *  of this object. If flush is true, all canvases are flushed after
+     *  draw.
      */
-    void draw();
+    void draw(bool flush = false);
 
     /**
      *  Abandon all buffered draws and reset to the initial state.
      */
     void reset();
 
 private:
     struct DrawData {
         SkCanvas*        fCanvas;  // reffed
         const SkPicture* fPicture; // reffed
         SkMatrix         fMatrix;
         SkPaint*         fPaint;   // owned
 
         void init(SkCanvas*, const SkPicture*, const SkMatrix*, const SkPaint*);
         void draw();
 
         static void Reset(SkTDArray<DrawData>&);
 
         static void Draw(DrawData* d) { d->draw(); }
     };
 
     SkTDArray<DrawData> fThreadSafeDrawData;
     SkTDArray<DrawData> fGPUDrawData;
 };
 
 #endif