Adds a new constructor for gfx::Image on iOS.

ui/gfx/image/image.h

Index: ui/gfx/image/image.h
diff --git a/ui/gfx/image/image.h b/ui/gfx/image/image.h
index bf0d9b455fcd6d00c623b41b5d9875dee867ef5d..18440165941b6c758b853165d0fc3ae579b36abe 100644
--- a/ui/gfx/image/image.h
+++ b/ui/gfx/image/image.h
@@ -72,6 +72,10 @@ class GFX_EXPORT Image {
 #if defined(OS_IOS)
   // Does not retain |image|; expects to take ownership.
   explicit Image(UIImage* image);
+
+  // Retains argument if |retain_argument| is true.
+  explicit Image(UIImage* image, bool retain_argument);

[sdefresne, 2016/11/22 14:23:16]

"explicit" is only for constructor that can be invoked with exactly one
argument. This is not the case here, so remove "explicit".

I don't really like using a bool parameter as it is always hard to understand
the call-sites. Since base::scoped_policy::OwnershipPolicy exists, can you use
that instead of a bool?

[stkhapugin, 2016/12/06 10:41:57]

Done

+
 #elif defined(OS_MACOSX)
   // Does not retain |image|; expects to take ownership.
   // A single NSImage object can contain multiple bitmaps so there's no reason