MacViews: Allow ui::EventLocationFromNative to handle native titlebars

ui/events/cocoa/events_mac.mm

Index: ui/events/cocoa/events_mac.mm
diff --git a/ui/events/cocoa/events_mac.mm b/ui/events/cocoa/events_mac.mm
index a8d93650b3610e402a5b7915be43d3bdec0035a8..13098ddb0b9bdb9662eeda3094a2bbdd2d49ab60 100644
--- a/ui/events/cocoa/events_mac.mm
+++ b/ui/events/cocoa/events_mac.mm
@@ -87,13 +87,14 @@ base::TimeDelta EventTimeFromNative(const base::NativeEvent& native_event) {
 }
 
 gfx::Point EventLocationFromNative(const base::NativeEvent& native_event) {
-  if (![native_event window]) {
+  NSWindow* window = [native_event window];
+  if (!window) {
     NOTIMPLEMENTED();  // Point will be in screen coordinates.
     return gfx::Point();
   }
   NSPoint location = [native_event locationInWindow];
-  return gfx::Point(location.x,
-                    NSHeight([[native_event window] frame]) - location.y);
+  NSRect content_rect = [window contentRectForFrameRect:[window frame]];
+  return gfx::Point(location.x, NSHeight(content_rect) - location.y);
 }

[tapted, 2014/06/05 07:33:35]

Note most of my local branches have been using a "ui/gfx/mac/point_utils.mm".
I'm not yet sure if it will be widely used, so haven't tried to land it. But
it's another possible approach for this stuff. Example in another CL:
https://codereview.chromium.org/303543004/diff/20001/ui/gfx/mac/point_utils.mm 

e.g. we could put a function in ui/gfx which was like

gfx::Point WindowPointFromNSPoint(NSWindow* window, const NSPoint& point) {
  if (!window)
    return ScreenPointFromNSPoint(point);
  NSRect content_rect = [window contentRectForFrameRect:[window frame]];
  return gfx::Point(location.x, NSHeight(content_rect) - location.y);
}

and here do

return gfx::WindowPointFromNSPoint([native_event window],
                                   [native_event locationInWindow]);

let me know if that approach sounds better.

[Robert Sesek, 2014/06/05 14:08:27]

I think I like extracting this information directly from the NSEvent better than
requiring the caller to pass the window.

 
 gfx::Point EventSystemLocationFromNative(