PPAPI: Make V8VarConverter longer-lived

content/renderer/pepper/message_channel.cc

Index: content/renderer/pepper/message_channel.cc
diff --git a/content/renderer/pepper/message_channel.cc b/content/renderer/pepper/message_channel.cc
index 490a6fb013fe0c387244c6205cd9d33d751ecbcd..ed8ee129aacfe5c482eb782dc3ff1bebc9ba1abb 100644
--- a/content/renderer/pepper/message_channel.cc
+++ b/content/renderer/pepper/message_channel.cc
@@ -122,8 +122,7 @@ void MessageChannel::PostMessageToJavaScript(PP_Var message_data) {
   v8::Context::Scope context_scope(context);
 
   v8::Handle<v8::Value> v8_val;
-  if (!V8VarConverter(instance_->pp_instance())
-           .ToV8Value(message_data, context, &v8_val)) {
+  if (!var_converter_.ToV8Value(message_data, context, &v8_val)) {
     PpapiGlobals::Get()->LogWithSource(instance_->pp_instance(),
                                        PP_LOGLEVEL_ERROR,
                                        std::string(),
@@ -187,6 +186,8 @@ MessageChannel::MessageChannel(PepperPluginInstanceImpl* instance)
       js_message_queue_state_(WAITING_TO_START),
       blocking_message_depth_(0),
       plugin_message_queue_state_(WAITING_TO_START),
+      var_converter_(instance->pp_instance(),
+                     V8VarConverter::kDisallowObjectVars),
       weak_ptr_factory_(this) {
 }
 
@@ -214,8 +215,7 @@ v8::Local<v8::Value> MessageChannel::GetNamedProperty(
   if (!instance_)
     return v8::Local<v8::Value>();
 
-  PepperTryCatchV8 try_catch(instance_, V8VarConverter::kDisallowObjectVars,
-                             isolate);
+  PepperTryCatchV8 try_catch(instance_, &var_converter_, isolate);
   if (identifier == kPostMessage) {
     return gin::CreateFunctionTemplate(isolate,
         base::Bind(&MessageChannel::PostMessageToNative,
@@ -246,8 +246,7 @@ bool MessageChannel::SetNamedProperty(v8::Isolate* isolate,
                                       v8::Local<v8::Value> value) {
   if (!instance_)
     return false;
-  PepperTryCatchV8 try_catch(instance_, V8VarConverter::kDisallowObjectVars,
-                             isolate);
+  PepperTryCatchV8 try_catch(instance_, &var_converter_, isolate);
   if (identifier == kPostMessage ||
       (identifier == kPostMessageAndAwaitResponse)) {
     try_catch.ThrowException("Cannot set properties with the name postMessage"
@@ -294,8 +293,7 @@ void MessageChannel::PostMessageToNative(gin::Arguments* args) {
 void MessageChannel::PostBlockingMessageToNative(gin::Arguments* args) {
   if (!instance_)
     return;
-  PepperTryCatchV8 try_catch(instance_, V8VarConverter::kDisallowObjectVars,
-                             args->isolate());
+  PepperTryCatchV8 try_catch(instance_, &var_converter_, args->isolate());
   if (args->Length() != 1) {
     try_catch.ThrowException(
         "postMessageAndAwaitResponse requires one argument");
@@ -389,14 +387,13 @@ PluginObject* MessageChannel::GetPluginObject(v8::Isolate* isolate) {
 
 void MessageChannel::EnqueuePluginMessage(v8::Handle<v8::Value> v8_value) {
   plugin_message_queue_.push_back(VarConversionResult());
-  // Convert NPVariantType_Object in to an appropriate PP_Var like Dictionary,
-  // Array, etc. Note NPVariantToVar would convert to an "Object" PP_Var,
-  // which we don't support for Messaging.
+  // Convert the v8 value in to an appropriate PP_Var like Dictionary,
+  // Array, etc. (We explicitly don't want an "Object" PP_Var, which we don't
+  // support for Messaging.)
   // TODO(raymes): Possibly change this to use TryCatch to do the conversion and
   // throw an exception if necessary.
-  V8VarConverter v8_var_converter(instance_->pp_instance());
   V8VarConverter::VarResult conversion_result =
-      v8_var_converter.FromV8Value(
+      var_converter_.FromV8Value(
           v8_value,
           v8::Isolate::GetCurrent()->GetCurrentContext(),
           base::Bind(&MessageChannel::FromV8ValueComplete,