Migrate ChromeOS to base::MemoryPressureMonitor

content/content_browser.gypi

 # 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.
 
 {
   'dependencies': [
     '../base/base.gyp:base_static',
     '../crypto/crypto.gyp:crypto',
     '../device/vibration/vibration.gyp:device_vibration',
     '../device/vibration/vibration.gyp:device_vibration_mojo_bindings',
@@ skipping 141 matching lines @@
       'public/browser/javascript_dialog_manager.h',
       'public/browser/load_from_memory_cache_details.cc',
       'public/browser/load_from_memory_cache_details.h',
       'public/browser/load_notification_details.h',
       'public/browser/local_storage_usage_info.cc',
       'public/browser/local_storage_usage_info.h',
       'public/browser/location_provider.h',
       'public/browser/media_capture_devices.h',
       'public/browser/media_device_id.cc',
       'public/browser/media_device_id.h',
-      'public/browser/memory_pressure_observer.h',
       'public/browser/message_port_delegate.h',
       'public/browser/message_port_provider.h',
       'public/browser/native_web_keyboard_event.h',
       'public/browser/navigation_controller.cc',
       'public/browser/navigation_controller.h',
       'public/browser/navigation_details.cc',
       'public/browser/navigation_details.h',
       'public/browser/navigation_entry.h',
       'public/browser/navigation_type.h',
       'public/browser/navigator_connect_context.h',
@@ skipping 1400 matching lines @@
       'browser/compositor/software_browser_compositor_output_surface.h',
       'browser/compositor/software_output_device_mac.h',
       'browser/compositor/software_output_device_mac.mm',
       'browser/compositor/software_output_device_ozone.cc',
       'browser/compositor/software_output_device_ozone.h',
       'browser/compositor/software_output_device_win.cc',
       'browser/compositor/software_output_device_win.h',
       'browser/compositor/software_output_device_x11.cc',
       'browser/compositor/software_output_device_x11.h',
       'browser/context_factory.cc',
-      'browser/memory_pressure_observer.cc',
     ],
     'plugin_browser_sources': [
       'browser/pepper_flash_settings_helper_impl.cc',
       'browser/pepper_flash_settings_helper_impl.h',
       'browser/plugin_content_origin_whitelist.cc',
       'browser/plugin_content_origin_whitelist.h',
       'browser/plugin_data_remover_impl.cc',
       'browser/plugin_data_remover_impl.h',
       'browser/plugin_loader_posix.cc',
       'browser/plugin_loader_posix.h',
@@ skipping 432 matching lines @@
         'browser/media/media_web_contents_observer.h',
       ],
     }],
     ['OS == "linux" and use_openssl==1', {
       'dependencies': [
         '../third_party/boringssl/boringssl.gyp:boringssl',
       ],
     }],
   ],
 }