[Mac] Placate the stupid compiler.

chrome/browser/ui/cocoa/draggable_button_mixin.mm

Index: chrome/browser/ui/cocoa/draggable_button_mixin.mm
diff --git a/chrome/browser/ui/cocoa/draggable_button_mixin.mm b/chrome/browser/ui/cocoa/draggable_button_mixin.mm
index a704498046064e48cb597e8f90ef40d896f2acc9..e28f674094255d9d81c95718a09ed152109f5045 100644
--- a/chrome/browser/ui/cocoa/draggable_button_mixin.mm
+++ b/chrome/browser/ui/cocoa/draggable_button_mixin.mm
@@ -64,7 +64,7 @@ const CGFloat kDragExpirationTimeout = 0.45;
 
 // NSButton/NSResponder Implementations ////////////////////////////////////////
 
-- (DraggableButtonResult)mouseUp:(NSEvent*)theEvent {
+- (DraggableButtonResult)mouseUpImpl:(NSEvent*)theEvent {
   durationMouseWasDown_ = [theEvent timestamp] - whenMouseDown_;
 
   if (actionHasFired_)
@@ -85,7 +85,7 @@ const CGFloat kDragExpirationTimeout = 0.45;
 
 // Mimic "begin a click" operation visually.  Do NOT follow through with normal
 // button event handling.
-- (DraggableButtonResult)mouseDown:(NSEvent*)theEvent {
+- (DraggableButtonResult)mouseDownImpl:(NSEvent*)theEvent {
   [[NSCursor arrowCursor] set];
 
   whenMouseDown_ = [theEvent timestamp];