PPAPI: Fix raymes's review comments I missed

content/renderer/pepper/message_channel.cc

 // Copyright (c) 2012 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 "content/renderer/pepper/message_channel.h"
 
 #include <cstdlib>
 #include <string>
 
 #include "base/bind.h"
@@ skipping 148 matching lines @@
 void MessageChannel::Start() {
   DCHECK_EQ(WAITING_TO_START, js_message_queue_state_);
   DCHECK_EQ(WAITING_TO_START, plugin_message_queue_state_);
 
   ppapi::proxy::HostDispatcher* dispatcher =
       ppapi::proxy::HostDispatcher::GetForInstance(instance_->pp_instance());
   // The dispatcher is NULL for in-process.
   if (dispatcher)
     dispatcher->AddSyncMessageStatusObserver(this);
 
-  // We can't drain the JS message queue directly
-  // since we haven't finished initializing the PepperWebPluginImpl yet, so
-  // the plugin isn't available in the DOM.
+  // We can't drain the JS message queue directly since we haven't finished
+  // initializing the PepperWebPluginImpl yet, so the plugin isn't available in
+  // the DOM.
   DrainJSMessageQueueSoon();
 
   plugin_message_queue_state_ = SEND_DIRECTLY;
   DrainCompletedPluginMessages();
 }
 
 void MessageChannel::SetPassthroughObject(v8::Handle<v8::Object> passthrough) {
   passthrough_object_.Reset(instance_->GetIsolate(), passthrough);
 }
 
@@ skipping 20 matching lines @@
   return Wrappable<MessageChannel>::GetObjectTemplateBuilder(isolate)
       .AddNamedPropertyInterceptor();
 }
 
 void MessageChannel::BeginBlockOnSyncMessage() {
   js_message_queue_state_ = QUEUE_MESSAGES;
   ++blocking_message_depth_;
 }
 
 void MessageChannel::EndBlockOnSyncMessage() {
+  DCHECK_GT(blocking_message_depth_, 0);
   --blocking_message_depth_;
   if (!blocking_message_depth_)
     DrainJSMessageQueueSoon();
 }
 
 v8::Local<v8::Value> MessageChannel::GetNamedProperty(
     v8::Isolate* isolate,
     const std::string& identifier) {
   if (!instance_)
     return v8::Local<v8::Value>();
@@ skipping 241 matching lines @@
 }
 
 void MessageChannel::DrainJSMessageQueueSoon() {
   base::MessageLoop::current()->PostTask(
       FROM_HERE,
       base::Bind(&MessageChannel::DrainJSMessageQueue,
                  weak_ptr_factory_.GetWeakPtr()));
 }
 
 }  // namespace content