ui/gfx/color_profile: implement GetDisplayColorProfile on mac

ui/gfx/color_profile.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.
 
 #ifndef UI_GFX_COLOR_PROFILE_H_
 #define UI_GFX_COLOR_PROFILE_H_
 
 #include <vector>
 
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/gfx_export.h"
 
 namespace gfx {
 
 static const size_t kMinProfileLength = 128;
 static const size_t kMaxProfileLength = 4 * 1024 * 1024;
 
 class GFX_EXPORT ColorProfile {
  public:
-  // On Windows, this reads a file from disk so it shouldn't be run on the UI
+  // On Windows, this reads a file from disk so it should not be run on the UI
   // or IO thread.
   ColorProfile();
   ~ColorProfile();
 
   const std::vector<char>& profile() const { return profile_; }
 
  private:
   std::vector<char> profile_;
 
   DISALLOW_COPY_AND_ASSIGN(ColorProfile);
 };
 
 inline bool InvalidColorProfileLength(size_t length) {
   return (length < kMinProfileLength) || (length > kMaxProfileLength);
 }
 
 // Return the color profile of the display nearest the screen bounds. On Win32,
-// this may read a file from disk, so it shouldn't be run on the UI/IO threads.
+// this may read a file from disk so it should not be run on the UI/IO threads.
 // If the given bounds are empty, or are off-screen, return false meaning there
-// is no color profile associated with the bounds.
+// is no color profile associated with the bounds.  Otherwise return true after
+// storing the display's color profile in |profile|, which will be empty if the
+// standard sRGB color profile should be assumed.
 GFX_EXPORT bool GetDisplayColorProfile(const gfx::Rect& bounds,
                                        std::vector<char>* profile);
 }  // namespace gfx
 
 #endif  // UI_GFX_COLOR_PROFILE_H_