Fix bug that causes spurious tab switches.

chrome/browser/ui/cocoa/tabs/tab_view.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/tabs/tab_view.h"
 
 #include "base/i18n/rtl.h"
 #include "base/logging.h"
 #include "base/mac/sdk_forward_declarations.h"
 #include "base/strings/sys_string_conversions.h"
@@ skipping 348 matching lines @@
       NSPoint hitLocation =
           [[self superview] convertPoint:[theEvent locationInWindow]
                                 fromView:nil];
       if ([self hitTest:hitLocation] == closeButton_) {
         [controller_ closeTab:self];
         return;
       }
     }
   }
 
-  // Fire the action to select the tab.
-  [controller_ selectTab:self];
-
-  // Messaging the drag controller with |-endDrag:| would seem like the right
-  // thing to do here. But, when a tab has been detached, the controller's
-  // target is nil until the drag is finalized. Since |-mouseUp:| gets called
-  // via the manual event loop inside -[TabStripDragController
-  // maybeStartDrag:forTab:], the drag controller can end the dragging session
-  // itself directly after calling this.
+  // Except in the rapid tab closure case, mouseDown: triggers a nested run loop
+  // that swallows the mouseUp: event. There's a bug in AppKit that sends
+  // mouseUp: callbacks to inappropriate views, so it's doubly important that
+  // this method doesn't do anything. https://crbug.com/511095.
+  [super mouseUp:theEvent];
 }
 
 - (void)otherMouseUp:(NSEvent*)theEvent {
   if ([self isClosing])
     return;
 
   // Support middle-click-to-close.
   if ([theEvent buttonNumber] == 2) {
     // |-hitTest:| takes a location in the superview's coordinates.
     NSPoint upLocation =
@@ skipping 643 matching lines @@
 
 // For "Increase Contrast" mode, use flat black instead of semitransparent black
 // for the tab edge stroke.
 + (void)setTabEdgeStrokeColor {
   static NSColor* heavyStrokeColor =
       [skia::SkColorToSRGBNSColor(SK_ColorBLACK) retain];
   [heavyStrokeColor set];
 }
 
 @end