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

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

 // Copyright (c) 2010 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.
 
 #ifndef CHROME_BROWSER_UI_COCOA_EXTENSIONS_BROWSER_ACTIONS_CONTAINER_VIEW_
 #define CHROME_BROWSER_UI_COCOA_EXTENSIONS_BROWSER_ACTIONS_CONTAINER_VIEW_
 
 #import <Cocoa/Cocoa.h>
 
 // Sent when a user-initiated drag to resize the container is initiated.
 extern NSString* const kBrowserActionGrippyDragStartedNotification;
 
 // Sent when a user-initiated drag is resizing the container.
 extern NSString* const kBrowserActionGrippyDraggingNotification;
 
 // Sent when a user-initiated drag to resize the container has finished.
 extern NSString* const kBrowserActionGrippyDragFinishedNotification;
 
+// Sent before the dragging will resize the container.
+extern NSString* const kBrowserActionGrippyWillDragNotification;
+
+// Key which is used to notify the translation with delta.
+extern NSString* const kTranslationWithDelta;
+
 // The view that encompasses the Browser Action buttons in the toolbar and
 // provides mechanisms for resizing.
 @interface BrowserActionsContainerView : NSView {
  @private
   // The frame encompasing the grippy used for resizing the container.
   NSRect grippyRect_;
 
   // The end frame of the animation currently running for this container or
   // NSZeroRect if none is in progress.
   NSRect animationEndFrame_;
@@ skipping 45 matching lines @@
 @property(nonatomic) BOOL canDragLeft;
 @property(nonatomic) BOOL canDragRight;
 @property(nonatomic) BOOL grippyPinned;
 @property(nonatomic,getter=isResizable) BOOL resizable;
 @property(nonatomic) CGFloat maxWidth;
 @property(readonly, nonatomic) BOOL userIsResizing;
 
 @end
 
 #endif  // CHROME_BROWSER_UI_COCOA_EXTENSIONS_BROWSER_ACTIONS_CONTAINER_VIEW_