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

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 5050c9ad4fe7bd8261a961bfeab6704f86287b51..b2ede647ad0b52cb33016a3018f624cc88fb1a47 100644
--- a/ui/gfx/image/image_skia.cc
+++ b/ui/gfx/image/image_skia.cc
@@ -276,7 +276,18 @@ std::vector<ImageSkiaRep> ImageSkia::image_reps() const {
   return image_reps;
 }
 
-ImageSkia::operator SkBitmap&() const {
+void ImageSkia::Init(const ImageSkiaRep& image_rep) {
+  // TODO(pkotwicz): The image should be null whenever image rep is null.
+  if (image_rep.sk_bitmap().empty()) {
+    storage_ = NULL;
+    return;
+  }
+  storage_ = new internal::ImageSkiaStorage(
+      NULL, gfx::Size(image_rep.GetWidth(), image_rep.GetHeight()));
+  storage_->image_reps().push_back(image_rep);
+}
+
+SkBitmap& ImageSkia::GetBitmap() const {
   if (isNull()) {
     // Callers expect a ImageSkiaRep even if it is |isNull()|.
     // TODO(pkotwicz): Fix this.
@@ -290,15 +301,4 @@ ImageSkia::operator SkBitmap&() const {
   return NullImageRep().mutable_sk_bitmap();
 }
 
-void ImageSkia::Init(const ImageSkiaRep& image_rep) {
-  // TODO(pkotwicz): The image should be null whenever image rep is null.
-  if (image_rep.sk_bitmap().empty()) {
-    storage_ = NULL;
-    return;
-  }
-  storage_ = new internal::ImageSkiaStorage(
-      NULL, gfx::Size(image_rep.GetWidth(), image_rep.GetHeight()));
-  storage_->image_reps().push_back(image_rep);
-}
-
 }  // namespace gfx