Optionally clear PlatformCanvas instances.

skia/ext/bitmap_platform_device_win.h

Index: skia/ext/bitmap_platform_device_win.h
===================================================================
--- skia/ext/bitmap_platform_device_win.h	(revision 123041)
+++ skia/ext/bitmap_platform_device_win.h	(working copy)
@@ -31,15 +31,16 @@
   // Factory function. The screen DC is used to create the bitmap, and will not
   // be stored beyond this function. is_opaque should be set if the caller
   // knows the bitmap will be completely opaque and allows some optimizations.
+  // initialize should be set if the bitmap needs to be initialized to zero.
   //
   // The shared_section parameter is optional (pass NULL for default behavior).
   // If shared_section is non-null, then it must be a handle to a file-mapping
   // object returned by CreateFileMapping.  See CreateDIBSection for details.
   static BitmapPlatformDevice* create(HDC screen_dc, int width, int height,
-                                      bool is_opaque, HANDLE shared_section);
+                                      int flags, HANDLE shared_section);
 
   // This version is the same as above but will get the screen DC itself.
-  static BitmapPlatformDevice* create(int width, int height, bool is_opaque,
+  static BitmapPlatformDevice* create(int width, int height, int flags,
                                       HANDLE shared_section);
 
   virtual ~BitmapPlatformDevice();