Fix app launcher animation tearing on OSX Mavericks.

ui/app_list/cocoa/app_list_view_controller.mm

 // Copyright 2013 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 "ui/app_list/cocoa/app_list_view_controller.h"
 
 #include "base/mac/foundation_util.h"
 #include "base/strings/string_util.h"
 #include "base/strings/sys_string_conversions.h"
 #include "skia/ext/skia_utils_mac.h"
@@ skipping 179 matching lines @@
   pagerControl_.reset([[AppListPagerView alloc] init]);
   [pagerControl_ setTarget:appsGridController_];
   [pagerControl_ setAction:@selector(onPagerClicked:)];
 
   NSRect gridFrame = [[appsGridController_ view] frame];
   NSRect contentsRect = NSMakeRect(0, kSearchInputHeight + kTopSeparatorSize,
       NSWidth(gridFrame), NSHeight(gridFrame) + kPagerPreferredHeight -
           [AppsGridController scrollerPadding]);
 
   contentsView_.reset([[FlippedView alloc] initWithFrame:contentsRect]);
+
+  // The contents view contains animations both from an NSCollectionView and the
+  // app list's own transitive drag layers. Ensure the subviews have access to
+  // a compositing layer they can share.
+  [contentsView_ setWantsLayer:YES];
+
   backgroundView_.reset(
       [[BackgroundView alloc] initWithFrame:
               NSMakeRect(0, 0, NSMaxX(contentsRect), NSMaxY(contentsRect))]);
   appsSearchBoxController_.reset(
       [[AppsSearchBoxController alloc] initWithFrame:
           NSMakeRect(0, 0, NSWidth(contentsRect), kSearchInputHeight)]);
   appsSearchResultsController_.reset(
       [[AppsSearchResultsController alloc] initWithAppsSearchResultsFrameSize:
           [contentsView_ bounds].size]);
   base::scoped_nsobject<NSView> containerView(
@@ skipping 156 matching lines @@
 
   [backgroundView_ setHidden:YES];
   signinViewController_.reset(
       [[SigninViewController alloc] initWithFrame:[backgroundView_ frame]
                                      cornerRadius:kBubbleCornerRadius
                                          delegate:signinDelegate]);
   [[self view] addSubview:[signinViewController_ view]];
 }
 
 @end