Implement externally_connectable! Web pages can now communicate directly with

chrome/renderer/extensions/runtime_custom_bindings.cc

Index: chrome/renderer/extensions/runtime_custom_bindings.cc
diff --git a/chrome/renderer/extensions/runtime_custom_bindings.cc b/chrome/renderer/extensions/runtime_custom_bindings.cc
index 0f4801fbc6ad3b93bb46297e8c3e7ca2bc92f2c4..587fcb738069487b719ee9ea1d3f47289938f17e 100644
--- a/chrome/renderer/extensions/runtime_custom_bindings.cc
+++ b/chrome/renderer/extensions/runtime_custom_bindings.cc
@@ -47,16 +47,14 @@ v8::Handle<v8::Value> RuntimeCustomBindings::OpenChannelToExtension(
     return v8::Undefined();
 
   // The Javascript code should validate/fill the arguments.
-  CHECK(args.Length() >= 3 &&
-        args[0]->IsString() &&
-        args[1]->IsString() &&
-        args[2]->IsString());
+  CHECK_EQ(2, args.Length());
+  CHECK(args[0]->IsString() && args[1]->IsString());
 
   ExtensionMsg_ExternalConnectionInfo info;
-  info.source_id = *v8::String::Utf8Value(args[0]->ToString());
-  info.target_id = *v8::String::Utf8Value(args[1]->ToString());
+  info.source_id = context()->extension() ? context()->extension()->id() : "";
+  info.target_id = *v8::String::Utf8Value(args[0]->ToString());
   info.source_url = renderview->GetWebView()->mainFrame()->document().url();
-  std::string channel_name = *v8::String::Utf8Value(args[2]->ToString());
+  std::string channel_name = *v8::String::Utf8Value(args[1]->ToString());
   int port_id = -1;
   renderview->Send(new ExtensionHostMsg_OpenChannelToExtension(
       renderview->GetRoutingID(), info, channel_name, &port_id));
@@ -103,4 +101,4 @@ v8::Handle<v8::Value> RuntimeCustomBindings::GetManifest(
                               context()->v8_context());
 }
 
-}  // extensions
+}  // namespace extensions