[Mac] Fix a potential crash in the permission bubble controller

chrome/browser/ui/cocoa/permission_bubble/permission_bubble_controller.mm

Index: chrome/browser/ui/cocoa/permission_bubble/permission_bubble_controller.mm
diff --git a/chrome/browser/ui/cocoa/permission_bubble/permission_bubble_controller.mm b/chrome/browser/ui/cocoa/permission_bubble/permission_bubble_controller.mm
index 9ad5c68e43fe5a396db84b65252d1411a1d36f77..11932109087d82ef940be27019c5b1c12cd82fbf 100644
--- a/chrome/browser/ui/cocoa/permission_bubble/permission_bubble_controller.mm
+++ b/chrome/browser/ui/cocoa/permission_bubble/permission_bubble_controller.mm
@@ -282,9 +282,10 @@ const NSInteger kFullscreenLeftOffset = 40;
 }
 
 - (void)showWindow:(id)sender {
-  if ([self hasVisibleLocationBar]) {
-    decoration_ = [[self.parentWindow windowController] locationBarBridge]
-                      ->GetPageInfoDecoration();
+  LocationBarViewMac* bridge =
+      [[self.parentWindow windowController] locationBarBridge];
+  if ([self hasVisibleLocationBar] && bridge) {
+    decoration_ = bridge->GetPageInfoDecoration();
     decoration_->SetActive(true);
   }