Mac: Fix for janky tab dragging/reordering.

chrome/browser/ui/cocoa/tabs/tab_strip_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/tabs/tab_strip_controller.h"
 
 #import <QuartzCore/QuartzCore.h>
 
 #include <cmath>
 #include <limits>
@@ skipping 1849 matching lines @@
 - (BOOL)inRapidClosureMode {
   return availableResizeWidth_ != kUseFullAvailableWidth;
 }
 
 // Disable tab dragging when there are any pending animations.
 - (BOOL)tabDraggingAllowed {
   return [closingControllers_ count] == 0;
 }
 
 - (void)mouseMoved:(NSEvent*)event {
+  // We don't want the draggged tab to repeatedly redraw its glow unnecessarily.
+  // We also want the dragged tab to keep the glow even when it slides behind
+  // another tab.
+  if ([dragController_ draggedTab])
+    return;
+
   // Use hit test to figure out what view we are hovering over.
   NSView* targetView = [tabStripView_ hitTest:[event locationInWindow]];
 
   // Set the new tab button hover state iff the mouse is over the button.
   BOOL shouldShowHoverImage = [targetView isKindOfClass:[NewTabButton class]];
   [self setNewTabButtonHoverState:shouldShowHoverImage];
 
   TabView* tabView = (TabView*)targetView;
   if (![tabView isKindOfClass:[TabView class]]) {
     if ([[tabView superview] isKindOfClass:[TabView class]]) {
@@ skipping 434 matching lines @@
   // up the hierarchy to the devtools container view to avoid that. Note that
   // the devtools view is always in the hierarchy even if it is not open or it
   // is detached.
   NSView* devtools_view = [[[view superview] superview] superview];
   if (devtools_view) {
     return [devtools_view convertRect:[devtools_view bounds] toView:nil];
   } else {
     return [view convertRect:[view bounds] toView:nil];
   }
 }