CoreAnimation: Reduce VA usage by extra layers

chrome/browser/ui/cocoa/tabs/tab_strip_drag_controller.mm

Index: chrome/browser/ui/cocoa/tabs/tab_strip_drag_controller.mm
diff --git a/chrome/browser/ui/cocoa/tabs/tab_strip_drag_controller.mm b/chrome/browser/ui/cocoa/tabs/tab_strip_drag_controller.mm
index 4bab57e2f0530961ff3f988e73868622816ae08d..841c46cb84c3d10d6834aea537e0ccb1e803ba5e 100644
--- a/chrome/browser/ui/cocoa/tabs/tab_strip_drag_controller.mm
+++ b/chrome/browser/ui/cocoa/tabs/tab_strip_drag_controller.mm
@@ -13,6 +13,7 @@
 #import "chrome/browser/ui/cocoa/tabs/tab_view.h"
 #import "chrome/browser/ui/cocoa/tabs/tab_window_controller.h"
 #import "chrome/browser/ui/cocoa/tabs/tab_strip_controller.h"
+#include "ui/gfx/mac/scoped_ns_disable_screen_updates.h"
 
 const CGFloat kTearDistance = 36.0;
 const NSTimeInterval kTearDuration = 0.333;
@@ -113,6 +114,11 @@ static BOOL PointIsInsideView(NSPoint screenPoint, NSView* view) {
                            untilDate:[NSDate distantFuture]
                               inMode:NSDefaultRunLoopMode
                              dequeue:YES];
+

[ccameron, 2014/04/19 02:45:29]

The dark background was popping through without this -- it turns out that this
fixes a lot of flickering issues during tab drag.

+    // Ensure that any window changes that happen while handling this event
+    // appear atomically.
+    gfx::ScopedNSDisableScreenUpdates disabler;
+
     NSEventType type = [theEvent type];
     if (type == NSKeyUp) {
       if ([theEvent keyCode] == kVK_Escape) {