Allow the creation of a skia::PlatformCanvas from a CGContextRef.

skia/ext/platform_canvas.h

Index: skia/ext/platform_canvas.h
diff --git a/skia/ext/platform_canvas.h b/skia/ext/platform_canvas.h
index b602ed46ca3e3aa3417ec7761c0eb9a617c1701d..1e51717f90d5b41f80995b89a2d68584663fcf83 100644
--- a/skia/ext/platform_canvas.h
+++ b/skia/ext/platform_canvas.h
@@ -47,6 +47,7 @@ class PlatformCanvas : public SkCanvas {
   PlatformCanvas(int width, int height, bool is_opaque, uint8_t* context);
 
   // For two-part init, call if you use the no-argument constructor above
+  bool initialize(CGContextRef context, int width, int height, bool is_opaque);
   bool initialize(int width, int height, bool is_opaque, uint8_t* data = NULL);
 
 #elif defined(__linux__) || defined(__FreeBSD__) || defined(__OpenBSD__) || \
@@ -106,6 +107,9 @@ class PlatformCanvas : public SkCanvas {
   // CoreGraphics.
   virtual SkDevice* setBitmapDevice(const SkBitmap& bitmap);
 
+  // Helper method used internally by the initialize() methods.
+  bool initializeWithDevice(SkDevice* device);
+
   // Disallow copy and assign.
   PlatformCanvas(const PlatformCanvas&);
   PlatformCanvas& operator=(const PlatformCanvas&);