Fixed overlapping subtle notifications on Mac.

chrome/browser/ui/cocoa/browser/exclusive_access_controller_views.mm

Index: chrome/browser/ui/cocoa/browser/exclusive_access_controller_views.mm
diff --git a/chrome/browser/ui/cocoa/browser/exclusive_access_controller_views.mm b/chrome/browser/ui/cocoa/browser/exclusive_access_controller_views.mm
index df37742bb1fe7934cf430f1c9d62a1745d12e123..40eb1a8327bfcd9b2e709663d42ac00c908a57f9 100644
--- a/chrome/browser/ui/cocoa/browser/exclusive_access_controller_views.mm
+++ b/chrome/browser/ui/cocoa/browser/exclusive_access_controller_views.mm
@@ -36,6 +36,9 @@ ExclusiveAccessController::~ExclusiveAccessController() {}
 
 void ExclusiveAccessController::Show() {
   if (ExclusiveAccessManager::IsSimplifiedFullscreenUIEnabled()) {
+    // Hide the backspace shortcut bubble, to avoid overlapping.
+    new_back_shortcut_bubble_.reset();
+
     views_bubble_.reset(
         new ExclusiveAccessBubbleViews(this, url_, bubble_type_));
     return;
@@ -52,6 +55,9 @@ void ExclusiveAccessController::Show() {
 }
 
 void ExclusiveAccessController::ShowNewBackShortcutBubble(bool forward) {
+  // Hide the exclusive access bubble, to avoid overlapping.
+  views_bubble_.reset();
+
   if (new_back_shortcut_bubble_)
     new_back_shortcut_bubble_->UpdateContent(forward);
   else