Free memory when the last WebView instance is destroyed.

android_webview/native/aw_contents.cc

 // Copyright 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 "android_webview/native/aw_contents.h"
 
 #include "android_webview/browser/aw_browser_context.h"
 #include "android_webview/browser/aw_browser_main_parts.h"
 #include "android_webview/browser/gpu_memory_buffer_factory_impl.h"
 #include "android_webview/browser/in_process_view_renderer.h"
 #include "android_webview/browser/net_disk_cache_remover.h"
 #include "android_webview/browser/renderer_host/aw_resource_dispatcher_host_delegate.h"
 #include "android_webview/common/aw_hit_test_data.h"
 #include "android_webview/native/aw_autofill_manager_delegate.h"
 #include "android_webview/native/aw_browser_dependency_factory.h"
 #include "android_webview/native/aw_contents_client_bridge.h"
 #include "android_webview/native/aw_contents_io_thread_client_impl.h"
 #include "android_webview/native/aw_picture.h"
 #include "android_webview/native/aw_web_contents_delegate.h"
 #include "android_webview/native/java_browser_view_renderer_helper.h"
 #include "android_webview/native/state_serializer.h"
 #include "android_webview/public/browser/draw_gl.h"
 #include "base/android/jni_android.h"
 #include "base/android/jni_array.h"
 #include "base/android/jni_string.h"
 #include "base/android/scoped_java_ref.h"
 #include "base/atomicops.h"
 #include "base/bind.h"
 #include "base/callback.h"
+#include "base/memory/memory_pressure_listener.h"
 #include "base/message_loop/message_loop.h"
 #include "base/pickle.h"
 #include "base/strings/string16.h"
 #include "base/supports_user_data.h"
 #include "components/autofill/content/browser/autofill_driver_impl.h"
 #include "components/autofill/core/browser/autofill_manager.h"
 #include "components/autofill/core/browser/webdata/autofill_webdata_service.h"
 #include "components/navigation_interception/intercept_navigation_delegate.h"
 #include "content/public/browser/android/content_view_core.h"
 #include "content/public/browser/browser_thread.h"
@@ skipping 203 matching lines @@
   base::subtle::NoBarrier_AtomicIncrement(&g_instance_count, -1);
 }
 
 jint AwContents::GetWebContents(JNIEnv* env, jobject obj) {
   DCHECK(web_contents_);
   return reinterpret_cast<jint>(web_contents_.get());
 }
 
 void AwContents::Destroy(JNIEnv* env, jobject obj) {
   delete this;
+
+  // When the last WebView is destroyed free all discardable memory allocated by
+  // Chromium, because the app process may continue to run for a long time
+  // without ever using another WebView.
+  if (base::subtle::NoBarrier_Load(&g_instance_count) == 0) {
+    base::MemoryPressureListener::NotifyMemoryPressure(
+        base::MemoryPressureListener::MEMORY_PRESSURE_CRITICAL);
+  }
 }
 
 static jint Init(JNIEnv* env, jclass, jobject browser_context) {
   // TODO(joth): Use |browser_context| to get the native BrowserContext, rather
   // than hard-code the default instance lookup here.
   scoped_ptr<WebContents> web_contents(content::WebContents::Create(
       content::WebContents::CreateParams(AwBrowserContext::GetDefault())));
   // Return an 'uninitialized' instance; most work is deferred until the
   // subsequent SetJavaPeers() call.
   return reinterpret_cast<jint>(new AwContents(web_contents.Pass()));
@@ skipping 533 matching lines @@
   browser_view_renderer_->EnableOnNewPicture(enabled);
 }
 
 void AwContents::SetJsOnlineProperty(JNIEnv* env,
                                      jobject obj,
                                      jboolean network_up) {
   render_view_host_ext_->SetJsOnlineProperty(network_up);
 }
 
 }  // namespace android_webview