Bind plugin placeholder directly to v8 instead of over CppBoundClass

components/plugins/renderer/plugin_placeholder.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/plugin_placeholder.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/json/string_escape.h"
 #include "base/strings/string_piece.h"
@@ skipping 16 matching lines @@
 using content::RenderThread;
 using blink::WebElement;
 using blink::WebFrame;
 using blink::WebMouseEvent;
 using blink::WebNode;
 using blink::WebPlugin;
 using blink::WebPluginContainer;
 using blink::WebPluginParams;
 using blink::WebScriptSource;
 using blink::WebURLRequest;
-using webkit_glue::CppArgumentList;
-using webkit_glue::CppVariant;
 
 namespace plugins {
 
+namespace {
+
+// This class is supposed to be stored in an v8::External. It holds a
+// base::Closure and will delete itself as soon as the v8::External is garbage
+// collected.
+class V8ClosureWrapper {
+ public:
+  V8ClosureWrapper(const base::Closure& closure) : closure_(closure) {}

[Bernhard Bauer, 2013/11/14 16:25:43]

Nit: add `explicit` to constructor

[jochen (gone - plz use gerrit), 2013/11/15 10:09:39]

Done.

+
+  void SetExternal(v8::Isolate* isolate, v8::Handle<v8::External> external) {
+    DCHECK(external_.IsEmpty());
+    external_.Reset(isolate, external);
+    external_.SetWeak(this, &V8ClosureWrapper::WeakCallback);
+  }
+
+  void Run() {
+    closure_.Run();
+  }
+
+ private:
+  static void WeakCallback(
+      const v8::WeakCallbackData<v8::External, V8ClosureWrapper>& data) {
+    V8ClosureWrapper* info = data.GetParameter();
+    info->external_.Reset();
+    delete info;
+  }
+
+  ~V8ClosureWrapper() {}
+
+  base::Closure closure_;
+  v8::Persistent<v8::External> external_;
+
+  DISALLOW_COPY_AND_ASSIGN(V8ClosureWrapper);
+};
+
+void RunV8ClosureWrapper(const v8::FunctionCallbackInfo<v8::Value>& args) {
+  V8ClosureWrapper* wrapper = reinterpret_cast<V8ClosureWrapper*>(
+      v8::External::Cast(*args.Data())->Value());
+  wrapper->Run();
+}
+
+}  // namespace
+
 PluginPlaceholder::PluginPlaceholder(content::RenderView* render_view,
                                      WebFrame* frame,
                                      const WebPluginParams& params,
                                      const std::string& html_data,
                                      GURL placeholderDataUrl)
     : content::RenderViewObserver(render_view),
       frame_(frame),
       plugin_params_(params),
       plugin_(WebViewPlugin::Create(this,
                                     render_view->GetWebkitPreferences(),
                                     html_data,
                                     placeholderDataUrl)),
       is_blocked_for_prerendering_(false),
       allow_loading_(false),
       hidden_(false),
-      finished_loading_(false) {}
+      finished_loading_(false),
+      weak_factory_(this) {
+  RegisterCallback("load");
+  RegisterCallback("hide");
+  RegisterCallback("didFinishLoading");
+}
 
 PluginPlaceholder::~PluginPlaceholder() {}
 
+void PluginPlaceholder::RegisterCallback(const std::string& callback) {
+  DCHECK(callbacks_.end() ==
+         std::find(callbacks_.begin(), callbacks_.end(), callback));
+  callbacks_.push_back(callback);
+}
+
+void PluginPlaceholder::Observe(const std::string& callback) {
+}
+
+void PluginPlaceholder::InternalObserve(const std::string& callback) {
+  if (callback == "load") {
+    RenderThread::Get()->RecordUserMetrics("Plugin_Load_Click");
+    LoadPlugin();
+  } else if (callback == "hide") {
+    RenderThread::Get()->RecordUserMetrics("Plugin_Hide_Click");
+    HidePlugin();
+  } else if (callback == "didFinishLoading") {
+    finished_loading_ = true;
+    if (message_.length() > 0)
+      UpdateMessage();
+  } else {
+    Observe(callback);
+  }
+}
+
 void PluginPlaceholder::BindWebFrame(WebFrame* frame) {
-  BindToJavascript(frame, "plugin");
-  BindCallback(
-      "load",
-      base::Bind(&PluginPlaceholder::LoadCallback, base::Unretained(this)));
-  BindCallback(
-      "hide",
-      base::Bind(&PluginPlaceholder::HideCallback, base::Unretained(this)));
-  BindCallback("didFinishLoading",
-               base::Bind(&PluginPlaceholder::DidFinishLoadingCallback,
-                          base::Unretained(this)));
+  v8::Isolate* isolate = v8::Isolate::GetCurrent();
+  v8::HandleScope handle_scope(isolate);
+  v8::Handle<v8::Context> context = frame->mainWorldScriptContext();
+
+  if (context.IsEmpty())
+    return;
+
+  v8::Context::Scope context_scope(context);
+
+  v8::Handle<v8::FunctionTemplate> plugin_template =
+      v8::FunctionTemplate::New();
+  v8::Handle<v8::Template> prototype = plugin_template->PrototypeTemplate();
+
+  for (std::vector<std::string>::const_iterator callback = callbacks_.begin();
+       callback != callbacks_.end();
+       ++callback) {
+    V8ClosureWrapper* wrapper =
+        new V8ClosureWrapper(base::Bind(&PluginPlaceholder::InternalObserve,

[Bernhard Bauer, 2013/11/14 16:25:43]

Out of curiosity, why do you do this instead of having the subclass directly
register an arbitrary callback?

[jochen (gone - plz use gerrit), 2013/11/15 10:09:39]

It strikes me as a safer to use API

[Bernhard Bauer, 2013/11/15 10:24:03]

Why is that? It means that the subclass has to find out which callback was
called, which is somewhat prone to typos if you compare the callback name to a
string constant. 

+                                        weak_factory_.GetWeakPtr(),
+                                        *callback));
+    v8::Handle<v8::External> wrapper_holder = v8::External::New(wrapper);
+    wrapper->SetExternal(isolate, wrapper_holder);
+    prototype->Set(
+        v8::String::New(callback->c_str()),
+        v8::FunctionTemplate::New(RunV8ClosureWrapper, wrapper_holder));
+  }
+
+  v8::Handle<v8::Object> global = context->Global();
+  global->Set(v8::String::New("plugin"),
+              plugin_template->GetFunction()->NewInstance());
 }
 
 void PluginPlaceholder::ReplacePlugin(WebPlugin* new_plugin) {
   CHECK(plugin_);
   if (!new_plugin) return;
   WebPluginContainer* container = plugin_->container();
   // Set the new plug-in on the container before initializing it.
   container->setPlugin(new_plugin);
   // Save the element in case the plug-in is removed from the page during
   // initialization.
@@ skipping 117 matching lines @@
   }
 
   // TODO(mmenke):  In the case of prerendering, feed into
   //                ChromeContentRendererClient::CreatePlugin instead, to
   //                reduce the chance of future regressions.
   WebPlugin* plugin =
       render_view()->CreatePlugin(frame_, plugin_info_, plugin_params_);
   ReplacePlugin(plugin);
 }
 
-void PluginPlaceholder::LoadCallback(const CppArgumentList& args,
-                                     CppVariant* result) {
-  RenderThread::Get()->RecordUserMetrics("Plugin_Load_Click");
-  LoadPlugin();
-}
-
-void PluginPlaceholder::HideCallback(const CppArgumentList& args,
-                                     CppVariant* result) {
-  RenderThread::Get()->RecordUserMetrics("Plugin_Hide_Click");
-  HidePlugin();
-}
-
-void PluginPlaceholder::DidFinishLoadingCallback(const CppArgumentList& args,
-                                                 CppVariant* result) {
-  finished_loading_ = true;
-  if (message_.length() > 0)
-    UpdateMessage();
-}
-
 void PluginPlaceholder::SetPluginInfo(
     const content::WebPluginInfo& plugin_info) {
   plugin_info_ = plugin_info;
 }
 
 const content::WebPluginInfo& PluginPlaceholder::GetPluginInfo() const {
   return plugin_info_;
 }
 
 void PluginPlaceholder::SetIdentifier(const std::string& identifier) {
   identifier_ = identifier;
 }
 
 blink::WebFrame* PluginPlaceholder::GetFrame() { return frame_; }
 
 const blink::WebPluginParams& PluginPlaceholder::GetPluginParams() const {
   return plugin_params_;
 }
 
 }  // namespace plugins