image: Remove operator for converting from SkBitmap to ImageSkia.

ui/gfx/image/image_skia.cc

Index: ui/gfx/image/image_skia.cc
diff --git a/ui/gfx/image/image_skia.cc b/ui/gfx/image/image_skia.cc
index 65f2d48741233911458e18986c57f6ea12c4d56c..f0b90a15ffa9601481de40cdf16f74076ce7610a 100644
--- a/ui/gfx/image/image_skia.cc
+++ b/ui/gfx/image/image_skia.cc
@@ -160,11 +160,6 @@ ImageSkia& ImageSkia::operator=(const ImageSkia& other) {
   return *this;
 }
 
-ImageSkia& ImageSkia::operator=(const SkBitmap& other) {
-  Init(ImageSkiaRep(other, ui::SCALE_FACTOR_100P));
-  return *this;
-}
-
 ImageSkia::~ImageSkia() {
 }