Plugin Placeholders: Factor out common BindWebFrame method into base class.

components/plugins/renderer/webview_plugin.cc

 // 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.
 
 #include "components/plugins/renderer/webview_plugin.h"
 
 #include "base/message_loop/message_loop.h"
 #include "base/metrics/histogram.h"
 #include "base/numerics/safe_conversions.h"
 #include "content/public/common/web_preferences.h"
@@ skipping 27 matching lines @@
 using blink::WebURLError;
 using blink::WebURLRequest;
 using blink::WebURLResponse;
 using blink::WebVector;
 using blink::WebView;
 using content::WebPreferences;
 
 WebViewPlugin::WebViewPlugin(WebViewPlugin::Delegate* delegate,
                              const WebPreferences& preferences)
     : delegate_(delegate),
-      container_(NULL),
+      container_(nullptr),
       web_view_(WebView::create(this)),
       finished_loading_(false),
       focused_(false) {
   // ApplyWebPreferences before making a WebLocalFrame so that the frame sees a
   // consistent view of our preferences.
   content::RenderView::ApplyWebPreferences(preferences, web_view_);
   web_frame_ = WebLocalFrame::create(blink::WebTreeScopeType::Document, this);
   web_view_->setMainFrame(web_frame_);
 }
 
 // static
 WebViewPlugin* WebViewPlugin::Create(WebViewPlugin::Delegate* delegate,
                                      const WebPreferences& preferences,
                                      const std::string& html_data,
                                      const GURL& url) {
+  DCHECK(url.is_valid()) << "Blink requires the WebView to have a valid URL.";
   WebViewPlugin* plugin = new WebViewPlugin(delegate, preferences);
   plugin->web_view()->mainFrame()->loadHTMLString(html_data, url);
   return plugin;
 }
 
 WebViewPlugin::~WebViewPlugin() {
   web_view_->close();
   web_frame_->close();
 }
 
@@ skipping 41 matching lines @@
     // Propagate device scale to inner webview to load the correct resource
     // when images have a "srcset" attribute.
     web_view_->setDeviceScaleFactor(container_->deviceScaleFactor());
   }
   return true;
 }
 
 void WebViewPlugin::destroy() {
   if (delegate_) {
     delegate_->PluginDestroyed();
-    delegate_ = NULL;
+    delegate_ = nullptr;
   }
-  container_ = NULL;
+  container_ = nullptr;
   base::MessageLoop::current()->DeleteSoon(FROM_HERE, this);
 }
 
 v8::Local<v8::Object> WebViewPlugin::v8ScriptableObject(v8::Isolate* isolate) {
   if (!delegate_)
     return v8::Local<v8::Object>();
 
   return delegate_->GetV8ScriptableObject(isolate);
 }
 
@@ skipping 116 matching lines @@
 void WebViewPlugin::didChangeCursor(const WebCursorInfo& cursor) {
   current_cursor_ = cursor;
 }
 
 void WebViewPlugin::scheduleAnimation() {
   if (container_)
     container_->invalidate();
 }
 
 void WebViewPlugin::didClearWindowObject(WebLocalFrame* frame) {
+  DCHECK_EQ(web_frame_, frame);
   if (delegate_)
     delegate_->BindWebFrame(frame);
 }
 
 void WebViewPlugin::didReceiveResponse(WebLocalFrame* frame,
                                        unsigned identifier,
                                        const WebURLResponse& response) {
   WebFrameClient::didReceiveResponse(frame, identifier, response);
 }