Add a full clear method to GrDrawTarget.

src/gpu/GrDrawTarget.h

 /*
  * Copyright 2010 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrDrawTarget_DEFINED
 #define GrDrawTarget_DEFINED
 
@@ skipping 103 matching lines @@
      * (if possible in the 3D API).  Note, we will never have an inverse
      * fill with stencil path
      */
     void stencilPath(GrDrawContext*,
                      const GrClip&,
                      const GrUserStencilSettings*,
                      bool useHWAA,
                      const SkMatrix& viewMatrix,
                      const GrPath*);
 
+    /** Clears the entire render target */
+    void fullClear(GrRenderTarget*, GrColor color);
+
     /** Discards the contents render target. */
     void discard(GrRenderTarget*);
 
     /**
      * Copies a pixel rectangle from one surface to another. This call may finalize
      * reserved vertex/index data (as though a draw call was made). The src pixels
      * copied are specified by srcRect. They are copied to a rect of the same
      * size in dst with top left at dstPoint. If the src rect is clipped by the
      * src bounds then  pixel values in the dst rect corresponding to area clipped
      * by the src rect are not overwritten. This method is not guaranteed to succeed
@@ skipping 97 matching lines @@
     bool                                            fDrawBatchBounds;
     int                                             fMaxBatchLookback;
     int                                             fMaxBatchLookahead;
 
     SkAutoTDelete<gr_instanced::InstancedRendering> fInstancedRendering;
 
     typedef SkRefCnt INHERITED;
 };
 
 #endif