Allow compressed texture data to be updated.

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 256 matching lines @@
                            GrGLenum* externalFormat,
                            GrGLenum* externalType);
     // helper for onCreateTexture and writeTexturePixels
     bool uploadTexData(const GrGLTexture::Desc& desc,
                        bool isNewTexture,
                        int left, int top, int width, int height,
                        GrPixelConfig dataConfig,
                        const void* data,
                        size_t rowBytes);
 
-    // helper for onCreateCompressedTexture
+    // helper for onCreateCompressedTexture. If width and height are
+    // set to -1, then this function will use desc.fWidth and desc.fHeight
+    // for the size of the data. The isNewTexture flag should be set to true
+    // whenever a new texture needs to be created. Otherwise, we assume that
+    // the texture is already in GPU memory and that it's going to be updated
+    // with new data.
     bool uploadCompressedTexData(const GrGLTexture::Desc& desc,
-                                 const void* data);
+                                 const void* data,
+                                 bool isNewTexture = true,
+                                 int left = 0, int top = 0,
+                                 int width = -1, int height = -1);
 
     bool createRenderTargetObjects(int width, int height,
                                    GrGLuint texID,
                                    GrGLRenderTarget::Desc* desc);
 
     GrGLContext fGLContext;
 
     // GL program-related state
     ProgramCache*               fProgramCache;
     SkAutoTUnref<GrGLProgram>   fCurrentProgram;
@@ skipping 181 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;
 
     SkAutoTDelete<GrGLNameAllocator> fPathNameAllocator;
 
     typedef GrGpu INHERITED;
 };
 
 #endif