Forward handling of low-mem message to the content renderer client. Add APIs to handle this case.

chrome/renderer/chrome_render_process_observer.cc

 // Copyright (c) 2011 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 "base/command_line.h"
 #include "base/file_util.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
 #include "base/native_library.h"
 #include "base/path_service.h"
 #include "base/process_util.h"
 #include "base/threading/platform_thread.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/extensions/extension_localization_peer.h"
 #include "chrome/common/net/net_resource_provider.h"
 #include "chrome/common/render_messages.h"
+#include "chrome/renderer/chrome_content_renderer_client.h"
 #include "chrome/renderer/content_settings_observer.h"
 #include "chrome/renderer/security_filter_peer.h"
 #include "content/common/resource_dispatcher.h"
 #include "content/common/resource_dispatcher_delegate.h"
 #include "content/common/view_messages.h"
 #include "content/renderer/render_thread.h"
 #include "content/renderer/render_view.h"
 #include "content/renderer/render_view_visitor.h"
 #include "crypto/nss_util.h"
 #include "media/base/media.h"
@@ skipping 268 matching lines @@
   const int shutdown_fd_;
 
   DISALLOW_COPY_AND_ASSIGN(ShutdownDetector);
 };
 #endif  // OS_MACOSX
 
 }  // namespace
 
 bool ChromeRenderProcessObserver::is_incognito_process_ = false;
 
-ChromeRenderProcessObserver::ChromeRenderProcessObserver() {
+ChromeRenderProcessObserver::ChromeRenderProcessObserver(
+    chrome::ChromeContentRendererClient* client)
+    : client_(client) {
   const CommandLine& command_line = *CommandLine::ForCurrentProcess();
   if (command_line.HasSwitch(switches::kEnableWatchdog)) {
     // TODO(JAR): Need to implement renderer IO msgloop watchdog.
   }
 
   if (command_line.HasSwitch(switches::kDumpHistogramsOnExit)) {
     base::StatisticsRecorder::set_dump_on_exit(true);
   }
 
   RenderThread* thread = RenderThread::current();
@@ skipping 176 matching lines @@
   // more to free").  Note that it makes more sense to do this than to implement
   // a new "delete everything" pass because object references make it difficult
   // to free everything possible in just one pass.
   while (!v8::V8::IdleNotification()) {
   }
 
 #if !defined(OS_MACOSX) && defined(USE_TCMALLOC)
   // Tell tcmalloc to release any free pages it's still holding.
   MallocExtension::instance()->ReleaseFreeMemory();
 #endif
+
+  if (client_)
+    client_->OnPurgeMemory();
 }