[Mac] Fix for AutofillPopupViewBridge Crash

Unsubscribe the WebTextfieldTouchBarController from
the notification center when it's deallocated or the
window it's observing is closed.

Bug: 747713
Change-Id: I9d3543775fadc9fda31f6de83c1b962218ce0a30
Reviewed-on: https://chromium-review.googlesource.com/583929
Commit-Queue: Sarah Chan <spqchan@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#489119}

chrome/browser/ui/cocoa/web_textfield_touch_bar_controller.h

@@ -19,6 +19,7 @@
 @interface WebTextfieldTouchBarController : NSObject<NSTouchBarDelegate> {
   TabContentsController* owner_;       // weak.
   AutofillPopupViewCocoa* popupView_;  // weak.
+  NSWindow* window_;                   // weak.
 }
 
 // Designated initializer.

chrome/browser/ui/cocoa/web_textfield_touch_bar_controller.mm

@@ -20,14 +20,22 @@ - (instancetype)initWithTabContentsController:(TabContentsController*)owner {
   return self;
 }
 
+- (void)dealloc {
+  [[NSNotificationCenter defaultCenter] removeObserver:self];
+  [super dealloc];
+}
+
 - (void)showCreditCardAutofillForPopupView:(AutofillPopupViewCocoa*)popupView {
   DCHECK(popupView);
   DCHECK([popupView window]);
+
+  window_ = [popupView window];
+
   NSNotificationCenter* center = [NSNotificationCenter defaultCenter];
   [center addObserver:self
              selector:@selector(popupWindowWillClose:)
                  name:NSWindowWillCloseNotification
-               object:[popupView window]];
+               object:window_];
   popupView_ = popupView;
 
   if ([owner_ respondsToSelector:@selector(setTouchBar:)])
@@ -39,6 +47,11 @@ - (void)popupWindowWillClose:(NSNotification*)notif {
 
   if ([owner_ respondsToSelector:@selector(setTouchBar:)])
     [owner_ performSelector:@selector(setTouchBar:) withObject:nil];
+
+  [[NSNotificationCenter defaultCenter]
+      removeObserver:self
+                name:NSWindowWillCloseNotification
+              object:window_];
 }
 
 - (NSTouchBar*)makeTouchBar {