cros: Only preload the lock screen; do not reuse it.

chrome/browser/chromeos/login/ui/shared_web_view.cc

-// Copyright 2016 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/browser/chromeos/login/ui/shared_web_view.h"
-
-#include "base/memory/ptr_util.h"
-#include "chrome/browser/chrome_notification_types.h"
-#include "chrome/browser/chromeos/login/ui/web_view_handle.h"
-#include "chrome/browser/profiles/profile.h"
-#include "content/public/browser/notification_service.h"
-#include "content/public/browser/render_view_host.h"
-#include "content/public/browser/render_widget_host.h"
-#include "content/public/browser/web_contents.h"
-#include "ui/views/controls/webview/webview.h"
-
-namespace chromeos {
-
-SharedWebView::SharedWebView(Profile* profile) : profile_(profile) {
-  registrar_.Add(this, chrome::NOTIFICATION_APP_TERMINATING,
-                 content::NotificationService::AllSources());
-  memory_pressure_listener_ = base::MakeUnique<base::MemoryPressureListener>(
-      base::Bind(&SharedWebView::OnMemoryPressure, base::Unretained(this)));
-}
-
-SharedWebView::~SharedWebView() {}
-
-void SharedWebView::Shutdown() {
-  web_view_handle_ = nullptr;
-}
-
-bool SharedWebView::Get(const GURL& url,
-                        scoped_refptr<WebViewHandle>* out_handle) {
-  // At the moment only one shared WebView instance is supported per profile.
-  DCHECK(web_view_url_.is_empty() || web_view_url_ == url);
-  web_view_url_ = url;
-
-  // Ensure the WebView is not being reused simultaneously.
-  DCHECK(!web_view_handle_ || web_view_handle_->HasOneRef());
-
-  // Clear cached reference if it is no longer valid (ie, destroyed in task
-  // manager).
-  if (web_view_handle_ &&
-      !web_view_handle_->web_view()
-           ->GetWebContents()
-           ->GetRenderViewHost()
-           ->GetWidget()
-           ->GetView()) {
-    web_view_handle_ = nullptr;
-  }
-
-  // Create WebView if needed.
-  bool reused = true;
-  if (!web_view_handle_) {
-    web_view_handle_ = new WebViewHandle(profile_);
-    reused = false;
-  }
-
-  *out_handle = web_view_handle_;
-  return reused;
-}
-
-void SharedWebView::Observe(int type,
-                            const content::NotificationSource& source,
-                            const content::NotificationDetails& details) {
-  DCHECK_EQ(chrome::NOTIFICATION_APP_TERMINATING, type);
-  web_view_handle_ = nullptr;
-}
-
-void SharedWebView::OnMemoryPressure(
-    base::MemoryPressureListener::MemoryPressureLevel level) {
-  switch (level) {
-    case base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE:
-      break;
-    case base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE:
-    case base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL:
-      web_view_handle_ = nullptr;
-      break;
-  }
-}
-
-}  // namespace chromeos