To ensure that the location bar will not reach the minimum width.

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

 // Copyright (c) 2012 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_controller.h"
 
 #include <cmath>
 #include <string>
 
 #include "base/strings/sys_string_conversions.h"
@@ skipping 101 matching lines @@
 - (void)containerDragStart:(NSNotification*)notification;
 
 // Sends a notification for the toolbar to reposition surrounding UI elements.
 - (void)containerDragging:(NSNotification*)notification;
 
 // Determines which buttons need to be hidden based on the new size, hides them
 // and updates the chevron overflow menu. Also fires a notification to let the
 // toolbar know that the drag has finished.
 - (void)containerDragFinished:(NSNotification*)notification;
 
+// Sends a notification for the toolbar to determine whether the container can
+// translate with a delta on x-axis.
+- (void)containerWillTranslateOnX:(NSNotification*)notification;
+
 // Adjusts the position of the surrounding action buttons depending on where the
 // button is within the container.
 - (void)actionButtonDragging:(NSNotification*)notification;
 
 // Updates the position of the Browser Actions within the container. This fires
 // when _any_ Browser Action button is done dragging to keep all open windows in
 // sync visually.
 - (void)actionButtonDragFinished:(NSNotification*)notification;
 
 // Moves the given button both visually and within the toolbar model to the
@@ skipping 175 matching lines @@
     [[NSNotificationCenter defaultCenter]
         addObserver:self
            selector:@selector(containerDragging:)
                name:kBrowserActionGrippyDraggingNotification
              object:containerView_];
     [[NSNotificationCenter defaultCenter]
         addObserver:self
            selector:@selector(containerDragFinished:)
                name:kBrowserActionGrippyDragFinishedNotification
              object:containerView_];
+    [[NSNotificationCenter defaultCenter]
+        addObserver:self
+           selector:@selector(containerWillTranslateOnX:)
+               name:kBrowseActionContainerWillTranslateOnXNotification
+             object:containerView_];
     // Listen for a finished drag from any button to make sure each open window
     // stays in sync.
     [[NSNotificationCenter defaultCenter]
       addObserver:self
          selector:@selector(actionButtonDragFinished:)
              name:kBrowserActionButtonDragEndNotification
            object:nil];
 
     chevronAnimation_.reset([[NSViewAnimation alloc] init]);
     [chevronAnimation_ gtm_setDuration:kAnimationDuration
@@ skipping 343 matching lines @@
   }
   [self updateGrippyCursors];
 
   toolbarModel_->SetVisibleIconCount([self visibleButtonCount]);
 
   [[NSNotificationCenter defaultCenter]
       postNotificationName:kBrowserActionGrippyDragFinishedNotification
                     object:self];
 }
 
+- (void)containerWillTranslateOnX:(NSNotification*)notification {
+  [[NSNotificationCenter defaultCenter]
+      postNotificationName:kBrowseActionContainerWillTranslateOnXNotification
+                    object:self
+                  userInfo:notification.userInfo];
+}
+
 - (void)actionButtonDragging:(NSNotification*)notification {
   if (![self chevronIsHidden])
     [self setChevronHidden:YES inFrame:[containerView_ frame] animate:YES];
 
   // Determine what index the dragged button should lie in, alter the model and
   // reposition the buttons.
   CGFloat dragThreshold = std::floor(kBrowserActionWidth / 2);
   BrowserActionButton* draggedButton = [notification object];
   NSRect draggedButtonFrame = [draggedButton frame];
 
@@ skipping 166 matching lines @@
   const extensions::ExtensionList& toolbar_items =
       toolbarModel_->toolbar_items();
   if (index < toolbar_items.size()) {
     const Extension* extension = toolbar_items[index].get();
     return [buttons_ objectForKey:base::SysUTF8ToNSString(extension->id())];
   }
   return nil;
 }
 
 @end