ui/gfx/color_profile: implement GetDisplayColorProfile on mac

ui/gfx/color_profile.h

Index: ui/gfx/color_profile.h
diff --git a/ui/gfx/color_profile.h b/ui/gfx/color_profile.h
index 790bfe57fffb941b1aa09d788b81bdf8c2cc0d02..37a5634ac91c7532051ccfeefd0491084322e94f 100644
--- a/ui/gfx/color_profile.h
+++ b/ui/gfx/color_profile.h
@@ -17,7 +17,7 @@ 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();
@@ -35,9 +35,11 @@ inline bool InvalidColorProfileLength(size_t length) {
 }
 
 // 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