[Mac] Activate notifications on mouse *up*.

ui/message_center/cocoa/notification_controller.mm

Index: ui/message_center/cocoa/notification_controller.mm
diff --git a/ui/message_center/cocoa/notification_controller.mm b/ui/message_center/cocoa/notification_controller.mm
index 7893e96d69cf911474ec1b07b4c8bc4357e8f14b..b14c26c2e88cedfec14638f37893352c7c60c5f8 100644
--- a/ui/message_center/cocoa/notification_controller.mm
+++ b/ui/message_center/cocoa/notification_controller.mm
@@ -184,12 +184,15 @@
   return self;
 }
 
-- (void)mouseDown:(NSEvent*)event {
-  if ([event type] != NSLeftMouseDown) {
-    [super mouseDown:event];
+- (void)mouseUp:(NSEvent*)event {
+  if (event.type != NSLeftMouseUp) {
+    [super mouseUp:event];
     return;
   }
-  [controller_ notificationClicked];
+  if (NSPointInRect([self convertPoint:event.locationInWindow fromView:nil],
+                    self.bounds)) {
+    [controller_ notificationClicked];
+  }
 }
 
 - (NSView*)hitTest:(NSPoint)point {