[Extensions Toolbar Mac] Adjust button threshold for hiding

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 <string>
 
 #include "base/strings/sys_string_conversions.h"
 #include "chrome/browser/ui/browser.h"
@@ skipping 613 matching lines @@
 }
 
 - (void)containerDragFinished:(NSNotification*)notification {
   for (BrowserActionButton* button in buttons_.get()) {
     NSRect buttonFrame = [button frame];
     if (NSContainsRect([containerView_ bounds], buttonFrame))
       continue;
 
     CGFloat intersectionWidth =
         NSWidth(NSIntersectionRect([containerView_ bounds], buttonFrame));
-    // Pad the threshold by 5 pixels in order to have the buttons hide more
-    // easily.
+    // Hide the button if it's not "mostly" visible. "Mostly" here equates to
+    // having three or fewer pixels hidden.
     if (([containerView_ grippyPinned] && intersectionWidth > 0) ||
-        (intersectionWidth <= (NSWidth(buttonFrame) / 2) + 5.0)) {
+        (intersectionWidth <= NSWidth(buttonFrame) - 3.0)) {
       [button setAlphaValue:0.0];
       [button removeFromSuperview];
     }
   }
 
   toolbarActionsBar_->OnResizeComplete(
       toolbarActionsBar_->IconCountToWidth([self visibleButtonCount]));
 
   [self updateGrippyCursors];
   [self resizeContainerToWidth:toolbarActionsBar_->GetPreferredSize().width()];
@@ skipping 190 matching lines @@
 - (ToolbarActionsBar*)toolbarActionsBar {
   return toolbarActionsBar_.get();
 }
 
 + (BrowserActionsController*)fromToolbarActionsBarDelegate:
     (ToolbarActionsBarDelegate*)delegate {
   return static_cast<ToolbarActionsBarBridge*>(delegate)->controller_for_test();
 }
 
 @end