[Mac] Maximise timer slack for background tabs

base/message_loop/message_pump_mac.h

 // 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.
 
 // The basis for all native run loops on the Mac is the CFRunLoop.  It can be
 // used directly, it can be used as the driving force behind the similar
 // Foundation NSRunLoop, and it can be used to implement higher-level event
 // loops such as the NSApplication event loop.
 //
 // This file introduces a basic CFRunLoop-based implementation of the
@@ skipping 19 matching lines @@
 #ifndef BASE_MESSAGE_LOOP_MESSAGE_PUMP_MAC_H_
 #define BASE_MESSAGE_LOOP_MESSAGE_PUMP_MAC_H_
 
 #include "base/message_loop/message_pump.h"
 
 #include "base/basictypes.h"
 
 #include <CoreFoundation/CoreFoundation.h>
 
 #include "base/memory/weak_ptr.h"
+#include "base/message_loop/timer_slack.h"
 
 #if defined(__OBJC__)
 #if defined(OS_IOS)
 #import <Foundation/Foundation.h>
 #else
 #import <AppKit/AppKit.h>
 
 // Clients must subclass NSApplication and implement this protocol if they use
 // MessagePumpMac.
 @protocol CrAppProtocol
@@ skipping 292 matching lines @@
   BASE_EXPORT static bool IsHandlingSendEvent();
 #endif  // !defined(OS_IOS)
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(MessagePumpMac);
 };
 
 }  // namespace base
 
 #endif  // BASE_MESSAGE_LOOP_MESSAGE_PUMP_MAC_H_