image-skia: Remove implicit conversion to SkBitmap on linux and chromeos.

ui/gfx/image/image_skia.h

Index: ui/gfx/image/image_skia.h
diff --git a/ui/gfx/image/image_skia.h b/ui/gfx/image/image_skia.h
index a32ee9fa9a9634203d560be8756c5709e4a9e876..7c729cb95b0205ce960c5a13b2cdf6b3839e8808 100644
--- a/ui/gfx/image/image_skia.h
+++ b/ui/gfx/image/image_skia.h
@@ -60,10 +60,12 @@ class UI_EXPORT ImageSkia {
   // done.
   ImageSkia& operator=(const SkBitmap& other);
 
+#if defined(OS_MACOSX) || defined(OS_WIN)
   // Converts to gfx::ImageSkiaRep and SkBitmap.
   // TODO(pkotwicz): This is temporary till conversion to gfx::ImageSkia is
   // done.
-  operator SkBitmap&() const;
+  operator SkBitmap&() const { return GetBitmap(); }
+#endif
 
   ~ImageSkia();
 
@@ -117,7 +119,7 @@ class UI_EXPORT ImageSkia {
   // This function should only be used in unittests and on platforms which do
   // not support scale factors other than 1x.
   // TODO(pkotwicz): Return null SkBitmap when the object has no 1x bitmap.
-  const SkBitmap* bitmap() const { return &operator SkBitmap&(); }
+  const SkBitmap* bitmap() const { return &GetBitmap(); }
 
   // Returns a vector with the image reps contained in this object.
   // There is no guarantee that this will return all images rep for
@@ -131,6 +133,8 @@ class UI_EXPORT ImageSkia {
   // If the image rep's bitmap is empty, ImageStorage is set to NULL.
   void Init(const gfx::ImageSkiaRep& image_rep);
 
+  SkBitmap& GetBitmap() const;
+
   // A refptr so that ImageRepSkia can be copied cheaply.
   scoped_refptr<internal::ImageSkiaStorage> storage_;
 };