Consolidate code monitoring low memory kills and OOM kills to MemoryKillsMonitor on ChromeOS.

chrome/browser/browser_process_impl.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.
 
 // When each service is created, we set a flag indicating this. At this point,
 // the service initialization could fail or succeed. This allows us to remember
 // if we tried to create a service, and not try creating it over and over if
 // the creation failed.
 
 #ifndef CHROME_BROWSER_BROWSER_PROCESS_IMPL_H_
 #define CHROME_BROWSER_BROWSER_PROCESS_IMPL_H_
 
 #include <stdint.h>
 
 #include <memory>
 #include <string>
 
 #include "base/debug/stack_trace.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/threading/non_thread_safe.h"
 #include "base/timer/timer.h"
 #include "build/build_config.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/lifetime/keep_alive_state_observer.h"
+#include "chrome/browser/memory/memory_kills_monitor.h"
 #include "chrome/common/features.h"
 #include "components/prefs/pref_change_registrar.h"
 #include "extensions/features/features.h"
 #include "printing/features/features.h"
 
 class ChromeChildProcessWatcher;
 class ChromeDeviceClient;
 class ChromeResourceDispatcherHostDelegate;
 class DevToolsAutoOpener;
 class RemoteDebuggingServer;
@@ skipping 303 matching lines @@
   std::unique_ptr<ChromeChildProcessWatcher> child_process_watcher_;
 
   std::unique_ptr<ChromeDeviceClient> device_client_;
 
 #if defined(OS_WIN) || defined(OS_MACOSX) || defined(OS_LINUX)
   // Any change to this #ifdef must be reflected as well in
   // chrome/browser/memory/tab_manager_browsertest.cc
   std::unique_ptr<memory::TabManager> tab_manager_;
 #endif
 
+#if defined(OS_CHROMEOS)

[sky, 2016/11/26 16:49:40]

If this is CHROMEOS specific, how come the include isn't only for chromeos? That
said, AFAICT this member isn't used by BrowserProcessImpl. Can it move to
ChromeBrowserMainPartsChromeos?

[cylee1, 2016/11/29 20:28:40]

You're right. Moved it to ChromeBrowserMainPartsChromeos.
Also only include memory_kills_monitor.[cc.h] in ChromeOS build in BUILD.gn 

+  memory::MemoryKillsMonitor::Handle memory_kills_monitor_handle_;
+#endif  // !defined(OS_ANDROID)
+
   shell_integration::DefaultWebClientState cached_default_web_client_state_;
 
   std::unique_ptr<PhysicalWebDataSource> physical_web_data_source_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserProcessImpl);
 };
 
 #endif  // CHROME_BROWSER_BROWSER_PROCESS_IMPL_H_