gfx::Image is now thread-safe.

ui/gfx/image/image.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // An Image wraps an image any flavor, be it platform-native GdkBitmap/NSImage,
 // or a SkBitmap. This also provides easy conversion to other image types
 // through operator overloading. It will cache the converted representations
 // internally to prevent double-conversion.
 //
 // The lifetime of both the initial representation and any converted ones are
@@ skipping 31 matching lines @@
 namespace gfx {
 struct ImagePNGRep;
 class ImageSkia;
 class Size;
 
 namespace internal {
 class ImageRep;
 class ImageStorage;
 }
 
+// An image, backed by zero or more equivalent representations. When a specific

[Robert Sesek, 2014/04/17 16:56:58]

The comment for this class is at the top of the file.

+// representation is requested, the image data is converted to the desired
+// representation and cached, if it is not already.
+//
+// Image objects are copyable and thread safe. However, there are no thread
+// safety guarantees about the individual representations.
 class GFX_EXPORT Image {
  public:
   enum RepresentationType {
     kImageRepGdk,
     kImageRepCocoa,
     kImageRepCocoaTouch,
     kImageRepCairo,
     kImageRepSkia,
     kImageRepPNG,
   };
 
-  typedef std::map<RepresentationType, internal::ImageRep*> RepresentationMap;
-
   // Creates an empty image with no representations.
   Image();
 
   // Creates a new image by copying the raw PNG-encoded input for use as the
   // default representation.
   explicit Image(const std::vector<ImagePNGRep>& image_reps);
 
   // Creates a new image by copying the ImageSkia for use as the default
   // representation.
   explicit Image(const ImageSkia& image);
@@ skipping 106 matching lines @@
  private:
   // Returns the type of the default representation.
   RepresentationType DefaultRepresentationType() const;
 
   // Returns the ImageRep of the appropriate type or NULL if there is no
   // representation of that type (and must_exist is false).
   internal::ImageRep* GetRepresentation(
       RepresentationType rep_type, bool must_exist) const;
 
   // Stores a representation into the map.
+  // NOTE: This is const, despite modifying the object's internal storage. It
+  // should only be used to add representations that are equivalent to an
+  // existing representation (i.e., it should not affect the externally visible
+  // state of the object).
   void AddRepresentation(internal::ImageRep* rep) const;
 
   // Internal class that holds all the representations. This allows the Image to
   // be cheaply copied.
   scoped_refptr<internal::ImageStorage> storage_;
 
   friend class ::ImageTest;
   friend class ::ImageMacTest;
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_IMAGE_IMAGE_H_