add peekPixels to SkCanvas and SkSurface

include/core/SkBitmapDevice.h

Index: include/core/SkBitmapDevice.h
diff --git a/include/core/SkBitmapDevice.h b/include/core/SkBitmapDevice.h
index e4f9b88a5e68b9f6c60adff3b0604d90a17039c2..be98c958829e2344b492ee7c96ea4219a0cd8d63 100644
--- a/include/core/SkBitmapDevice.h
+++ b/include/core/SkBitmapDevice.h
@@ -82,6 +82,8 @@ public:
     */
     virtual SkBitmap::Config config() const SK_OVERRIDE { return fBitmap.config(); }
 
+    virtual SkImageInfo imageInfo() const SK_OVERRIDE;
+
     /**
      *  DEPRECATED: This will be made protected once WebKit stops using it.
      *              Instead use Canvas' writePixels method.
@@ -278,6 +280,7 @@ private:
     virtual void flush() SK_OVERRIDE {}
 
     virtual SkSurface* newSurface(const SkImageInfo&) SK_OVERRIDE;
+    virtual const void* peekPixels(SkImageInfo*, size_t* rowBytes) SK_OVERRIDE;
 
     SkBitmap    fBitmap;