[MacViews] Enable dragging a window by its caption/draggable areas.

ui/views/cocoa/bridged_content_view.h

Index: ui/views/cocoa/bridged_content_view.h
diff --git a/ui/views/cocoa/bridged_content_view.h b/ui/views/cocoa/bridged_content_view.h
index 0d84c779483eaa2ecd31e9def7cd0b73c4826c8f..2b55cfebcaf1a0c857708649395257a42efc750e 100644
--- a/ui/views/cocoa/bridged_content_view.h
+++ b/ui/views/cocoa/bridged_content_view.h
@@ -35,11 +35,18 @@ class View;
 
   // Whether the view is reacting to a keyDown event on the view.
   BOOL inKeyDown_;
+
+  // Whether dragging on the view moves the window.
+  BOOL mouseDownCanMoveWindow_;
 }
 
 @property(readonly, nonatomic) views::View* hostedView;
 @property(assign, nonatomic) ui::TextInputClient* textInputClient;
 
+// This usually returns YES if the view is transparent. We want to control it
+// so that BridgedNativeWidget can dynamically enable dragging of the window.
+@property(assign, nonatomic) BOOL mouseDownCanMoveWindow;
+
 // Initialize the NSView -> views::View bridge. |viewToHost| must be non-NULL.
 - (id)initWithView:(views::View*)viewToHost;