Fix a bug that was preventing rapid tab closure from working on Mac.

chrome/browser/ui/cocoa/tabs/tab_strip_controller.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/tabs/tab_strip_controller.h"
 
 #import <QuartzCore/QuartzCore.h>
 
 #include <limits>
 #include <string>
@@ skipping 822 matching lines @@
   if (verticalLayout_) {
     availableSpace = NSHeight([tabStripView_ bounds]);
   } else {
     if ([self inRapidClosureMode]) {
       availableSpace = availableResizeWidth_;
     } else {
       availableSpace = NSWidth([tabStripView_ frame]);
 
       // Account for the width of the new tab button.
       availableSpace -= NSWidth([newTabButton_ frame]) + kNewTabButtonOffset;
+
+      // Account for the right-side controls if not in rapid closure mode.
+      // (In rapid closure mode, the available width is set based on the
+      // position of the rightmost tab, not based on the width of the tab strip,
+      // so the right controls have already been accounted for.)
+      availableSpace -= [self rightIndentForControls];
     }
+
+    // Need to leave room for the left-side controls even in rapid closure mode.
     availableSpace -= [self leftIndentForControls];
-    availableSpace -= [self rightIndentForControls];
   }
 
   // This may be negative, but that's okay (taken care of by |MAX()| when
   // calculating tab sizes). "mini" tabs in horizontal mode just get a special
   // section, they don't change size.
   CGFloat availableSpaceForNonMini = availableSpace;
   if (!verticalLayout_) {
       availableSpaceForNonMini -=
           [self numberOfOpenMiniTabs] * (kMiniTabWidth - kTabOverlap);
   }
@@ skipping 1165 matching lines @@
   NSInteger index = [self indexFromModelIndex:modelIndex];
   BrowserWindowController* controller =
       (BrowserWindowController*)[[switchView_ window] windowController];
   DCHECK(index >= 0);
   if (index >= 0) {
     [controller setTab:[self viewAtIndex:index] isDraggable:YES];
   }
 }
 
 @end