Remove forceRenderTargetFlush (unused)

src/gpu/gl/GrGpuGL.h

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrGpuGL_DEFINED
 #define GrGpuGL_DEFINED
 
@@ skipping 118 matching lines @@
     virtual GrRenderTarget* onWrapBackendRenderTarget(const GrBackendRenderTargetDesc&) SK_OVERRIDE;
     virtual bool createStencilBufferForRenderTarget(GrRenderTarget* rt,
                                                     int width,
                                                     int height) SK_OVERRIDE;
     virtual bool attachStencilBufferToRenderTarget(
         GrStencilBuffer* sb,
         GrRenderTarget* rt) SK_OVERRIDE;
 
     virtual void onClear(const SkIRect* rect, GrColor color, bool canIgnoreRect) SK_OVERRIDE;
 
-    virtual void onForceRenderTargetFlush() SK_OVERRIDE;
-
     virtual bool onReadPixels(GrRenderTarget* target,
                               int left, int top,
                               int width, int height,
                               GrPixelConfig,
                               void* buffer,
                               size_t rowBytes) SK_OVERRIDE;
 
     virtual bool onWriteTexturePixels(GrTexture* texture,
                                       int left, int top, int width, int height,
                                       GrPixelConfig config, const void* buffer,
@@ skipping 305 matching lines @@
     ///@}
 
     // we record what stencil format worked last time to hopefully exit early
     // from our loop that tries stencil formats and calls check fb status.
     int fLastSuccessfulStencilFmtIdx;
 
     typedef GrGpu INHERITED;
 };
 
 #endif