[Extensions UI Mac] Don't let the top-level actions container be first responder

chrome/browser/ui/cocoa/extensions/browser_actions_container_view.mm

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "chrome/browser/ui/cocoa/extensions/browser_actions_container_view.h"
 
 #include <algorithm>
 #include <utility>
 
 #import "chrome/browser/ui/cocoa/view_id_util.h"
@@ skipping 178 matching lines @@
     resizable_ = !isOverflow_;
     [self setNeedsDisplay:YES];
   }
 }
 
 - (void)resetCursorRects {
   [self addCursorRect:grippyRect_ cursor:[self appropriateCursorForGrippy]];
 }
 
 - (BOOL)acceptsFirstResponder {
-  return YES;
+  // The overflow container needs to receive key events to handle in-item
+  // navigation. The top-level container should not become first responder,
+  // allowing focus travel to proceed to the first action.
+  return isOverflow_;
 }
 
 - (void)mouseEntered:(NSEvent*)theEvent {
   [[NSNotificationCenter defaultCenter]
       postNotificationName:kBrowserActionsContainerMouseEntered
                     object:self];
 }
 
 - (void)mouseDown:(NSEvent*)theEvent {
   initialDragPoint_ = [self convertPoint:[theEvent locationInWindow]
@@ skipping 161 matching lines @@
     retVal = [NSCursor resizeLeftRightCursor];
   }
   return retVal;
 }
 
 - (CGFloat)maxAllowedWidth {
   return delegate_ ? delegate_->GetMaxAllowedWidth() : CGFLOAT_MAX;
 }
 
 @end