[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 36 matching lines @@
 
   // Subclasses should implement the work they need to do in MessagePump::Run
   // in the DoRun method.  MessagePumpCFRunLoopBase::Run calls DoRun directly.
   // This arrangement is used because MessagePumpCFRunLoopBase needs to set
   // up and tear down things before and after the "meat" of DoRun.
   virtual void Run(Delegate* delegate) OVERRIDE;
   virtual void DoRun(Delegate* delegate) = 0;
 
   virtual void ScheduleWork() OVERRIDE;
   virtual void ScheduleDelayedWork(const TimeTicks& delayed_work_time) OVERRIDE;
+  virtual void SetTimerSlack(TimerSlack timer_slack) OVERRIDE;
 
  protected:
   // Accessors for private data members to be used by subclasses.
   CFRunLoopRef run_loop() const { return run_loop_; }
   int nesting_level() const { return nesting_level_; }
   int run_nesting_level() const { return run_nesting_level_; }
 
   // Sets this pump's delegate.  Signals the appropriate sources if
   // |delegateless_work_| is true.  |delegate| can be NULL.
   void SetDelegate(Delegate* delegate);
@@ skipping 82 matching lines @@
 
   // (weak) Delegate passed as an argument to the innermost Run call.
   Delegate* delegate_;
 
   // The time that delayed_work_timer_ is scheduled to fire.  This is tracked
   // independently of CFRunLoopTimerGetNextFireDate(delayed_work_timer_)
   // to be able to reset the timer properly after waking from system sleep.
   // See PowerStateNotification.
   CFAbsoluteTime delayed_work_fire_time_;
 
+  base::TimerSlack timer_slack_;
+
   // The recursion depth of the currently-executing CFRunLoopRun loop on the
   // run loop's thread.  0 if no run loops are running inside of whatever scope
   // the object was created in.
   int nesting_level_;
 
   // The recursion depth (calculated in the same way as nesting_level_) of the
   // innermost executing CFRunLoopRun loop started by a call to Run.
   int run_nesting_level_;
 
   // The deepest (numerically highest) recursion depth encountered since the
@@ skipping 134 matching lines @@
   static bool IsHandlingSendEvent();
 #endif  // !defined(OS_IOS)
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(MessagePumpMac);
 };
 
 }  // namespace base
 
 #endif  // BASE_MESSAGE_LOOP_MESSAGE_PUMP_MAC_H_