Only create chromeHidden object when needed.

chrome/renderer/extensions/chrome_v8_context.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/extensions/chrome_v8_context.h"
 
 #include "base/logging.h"
 #include "base/string_split.h"
 #include "base/values.h"
 #include "chrome/common/extensions/extension_set.h"
 #include "chrome/renderer/extensions/chrome_v8_extension.h"
 #include "content/public/renderer/render_view.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebFrame.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebView.h"
 #include "v8/include/v8.h"
 
+namespace {
+
+const char kChromeHidden[] = "chromeHidden";
+
+#ifndef NDEBUG
+const char kValidateCallbacks[] = "validateCallbacks";
+#endif
+
+}  // namespace
+
+
 ChromeV8Context::ChromeV8Context(v8::Handle<v8::Context> v8_context,
                                  WebKit::WebFrame* web_frame,
                                  const std::string& extension_id)
     : v8_context_(v8::Persistent<v8::Context>::New(v8_context)),
       web_frame_(web_frame),
       extension_id_(extension_id) {
   VLOG(1) << "Created context for extension\n"
           << "  id:    " << extension_id << "\n"
           << "  frame: " << web_frame_;
 }
 
 ChromeV8Context::~ChromeV8Context() {
   VLOG(1) << "Destroyed context for extension\n"
           << "  id:    " << extension_id_;
   v8_context_.Dispose();
 }
 
+// static
+v8::Handle<v8::Value> ChromeV8Context::GetOrCreateChromeHidden(
+    v8::Handle<v8::Context> context) {
+  v8::Local<v8::Object> global = context->Global();
+  v8::Local<v8::Value> hidden = global->GetHiddenValue(
+      v8::String::New(kChromeHidden));
+
+  if (hidden.IsEmpty() || hidden->IsUndefined()) {
+    hidden = v8::Object::New();
+    global->SetHiddenValue(v8::String::New(kChromeHidden), hidden);
+
+#ifndef NDEBUG
+    // Tell schema_generated_bindings.js to validate callbacks and events
+    // against their schema definitions in api/extension_api.json.
+    v8::Local<v8::Object>::Cast(hidden)
+        ->Set(v8::String::New(kValidateCallbacks), v8::True());
+#endif
+  }
+
+  DCHECK(hidden->IsObject());
+  return v8::Local<v8::Object>::Cast(hidden);
+}
+
+v8::Handle<v8::Value> ChromeV8Context::GetChromeHidden() const {
+  v8::Local<v8::Object> global = v8_context_->Global();
+  return global->GetHiddenValue(v8::String::New(kChromeHidden));
+}
+
 content::RenderView* ChromeV8Context::GetRenderView() const {
   if (web_frame_ && web_frame_->view())
     return content::RenderView::FromWebView(web_frame_->view());
   else
     return NULL;
 }
 
 bool ChromeV8Context::CallChromeHiddenMethod(
     const std::string& function_name,
     int argc,
     v8::Handle<v8::Value>* argv,
     v8::Handle<v8::Value>* result) const {
   v8::Context::Scope context_scope(v8_context_);
 
   // Look up the function name, which may be a sub-property like
   // "Port.dispatchOnMessage" in the hidden global variable.
-  v8::Local<v8::Value> value = v8::Local<v8::Value>::New(
-      ChromeV8Extension::GetChromeHidden(v8_context_));
+  v8::Local<v8::Value> value = v8::Local<v8::Value>::New(GetChromeHidden());
+  if (value.IsEmpty())
+    return false;
+
   std::vector<std::string> components;
   base::SplitStringDontTrim(function_name, '.', &components);
   for (size_t i = 0; i < components.size(); ++i) {
     if (!value.IsEmpty()) {
       value = v8::Local<v8::Object>::Cast(value)->Get(
           v8::String::New(components[i].c_str()));
     }
   }
 
   // TODO(aa): CHECK that this succeeds. Can't do this now because not all
@@ skipping 18 matching lines @@
   argv[0] = v8::String::New(extension_id_.c_str());
   argv[1] = v8::Boolean::New(is_extension_process);
   argv[2] = v8::Boolean::New(is_incognito_process);
   CallChromeHiddenMethod("dispatchOnLoad", arraysize(argv), argv, NULL);
 }
 
 void ChromeV8Context::DispatchOnUnloadEvent() const {
   v8::HandleScope handle_scope;
   CallChromeHiddenMethod("dispatchOnUnload", 0, NULL, NULL);
 }