Replace blink::WebDiscardableMemory with base::DiscardableMemory.

content/content_child.gypi

 # Copyright 2013 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',
     '../components/mime_util/mime_util.gyp:mime_util',
     '../components/scheduler/scheduler.gyp:scheduler',
     '../components/tracing.gyp:tracing',
@@ skipping 239 matching lines @@
       'child/sync_load_response.cc',
       'child/sync_load_response.h',
       'child/thread_safe_sender.cc',
       'child/thread_safe_sender.h',
       'child/v8_value_converter_impl.cc',
       'child/v8_value_converter_impl.h',
       'child/web_data_consumer_handle_impl.cc',
       'child/web_data_consumer_handle_impl.h',
       'child/web_database_observer_impl.cc',
       'child/web_database_observer_impl.h',
-      'child/web_discardable_memory_impl.cc',
-      'child/web_discardable_memory_impl.h',
       'child/web_url_loader_impl.cc',
       'child/web_url_loader_impl.h',
       'child/web_url_request_util.cc',
       'child/web_url_request_util.h',
       'child/webblobregistry_impl.cc',
       'child/webblobregistry_impl.h',
       'child/webfallbackthemeengine_impl.cc',
       'child/webfallbackthemeengine_impl.h',
       'child/webfileutilities_impl.cc',
       'child/webfileutilities_impl.h',
@@ skipping 48 matching lines @@
         'child/npapi/webplugin_delegate_impl_mac.mm',
       ],
     }],
     ['OS=="win"', {
       'sources!': [
         'child/npapi/webplugin_delegate_impl_aura.cc',
       ],
     }],
   ],
 }