[Mac] Maximise timer slack for background tabs

chrome/renderer/chrome_render_process_observer.cc

 // 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.
 
 #include "chrome/renderer/chrome_render_process_observer.h"
 
 #include <limits>
 #include <vector>
 
 #include "base/allocator/allocator_extension.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/file_util.h"
 #include "base/memory/weak_ptr.h"
 #include "base/message_loop/message_loop.h"
+#include "base/message_loop/timer_slack.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
 #include "base/metrics/statistics_recorder.h"
 #include "base/native_library.h"
 #include "base/path_service.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/threading/platform_thread.h"
 #include "chrome/common/child_process_logging.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/common/chrome_switches.h"
@@ skipping 280 matching lines @@
     IPC_MESSAGE_HANDLER(ChromeViewMsg_SetIsIncognitoProcess,
                         OnSetIsIncognitoProcess)
     IPC_MESSAGE_HANDLER(ChromeViewMsg_SetCacheCapacities, OnSetCacheCapacities)
     IPC_MESSAGE_HANDLER(ChromeViewMsg_ClearCache, OnClearCache)
     IPC_MESSAGE_HANDLER(ChromeViewMsg_SetFieldTrialGroup, OnSetFieldTrialGroup)
     IPC_MESSAGE_HANDLER(ChromeViewMsg_GetV8HeapStats, OnGetV8HeapStats)
     IPC_MESSAGE_HANDLER(ChromeViewMsg_GetCacheResourceStats,
                         OnGetCacheResourceStats)
     IPC_MESSAGE_HANDLER(ChromeViewMsg_SetContentSettingRules,
                         OnSetContentSettingRules)
+     IPC_MESSAGE_HANDLER(ChromeViewMsg_SetCoalesceTimers,
+                         OnSetTimerCoalescing)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
   return handled;
 }
 
 void ChromeRenderProcessObserver::WebKitInitialized() {
   webkit_initialized_ = true;
   if (pending_cache_capacity_ != kUnitializedCacheCapacity) {
     WebCache::setCapacities(pending_cache_min_dead_capacity_,
                             pending_cache_max_dead_capacity_,
@@ skipping 21 matching lines @@
 void ChromeRenderProcessObserver::OnSetIsIncognitoProcess(
     bool is_incognito_process) {
   is_incognito_process_ = is_incognito_process;
 }
 
 void ChromeRenderProcessObserver::OnSetContentSettingRules(
     const RendererContentSettingRules& rules) {
   content_setting_rules_ = rules;
 }
 
+void ChromeRenderProcessObserver::OnSetTimerCoalescing(bool enabled) {
+  base::TimerSlack timer_slack = base::TIMER_SLACK_NONE;
+  if (enabled)
+    timer_slack = base::TIMER_SLACK_MAXIMUM;
+  base::SetTimerSlack(timer_slack);
+}
+
 void ChromeRenderProcessObserver::OnSetCacheCapacities(size_t min_dead_capacity,
                                                        size_t max_dead_capacity,
                                                        size_t capacity) {
   if (!webkit_initialized_) {
     pending_cache_min_dead_capacity_ = min_dead_capacity;
     pending_cache_max_dead_capacity_ = max_dead_capacity;
     pending_cache_capacity_ = capacity;
     return;
   }
 
@@ skipping 37 matching lines @@
   if (clear_cache_pending_ && webkit_initialized_) {
     clear_cache_pending_ = false;
     WebCache::clear();
   }
 }
 
 const RendererContentSettingRules*
 ChromeRenderProcessObserver::content_setting_rules() const {
   return &content_setting_rules_;
 }