[nacltoons] Rename core classes in accordance with doc.

nacltoons/src/level_layer.h

 // Copyright (c) 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.
-#ifndef PHYSICS_LAYER_H_
-#define PHYSICS_LAYER_H_
+#ifndef LEVEL_LAYER_H_
+#define LEVEL_LAYER_H_
 
 #include "cocos2d.h"
 #include "CCLuaStack.h"
 #include "Box2D/Box2D.h"
 
 #ifdef COCOS2D_DEBUG
 #include "GLES-Render.h"
 #endif
 
 USING_NS_CC;
 
 typedef std::vector<cocos2d::CCPoint> PointList;
 
 /**
- * Physics layer that the user interacts with.
+ * Lavel layer in which gameplay takes place.  This layer contains
+ * the box2d world simulation.
  */
-class PhysicsLayer : public CCLayerColor, public b2ContactListener {
+class LevelLayer : public CCLayerColor, public b2ContactListener {
  public:
-  PhysicsLayer(int level_number);
-  ~PhysicsLayer();
+  LevelLayer(int level_number);
+  ~LevelLayer();
 
-  static PhysicsLayer* create(int level_number);
+  static LevelLayer* create(int level_number);
 
   virtual bool init();
   virtual void draw();
   virtual bool ccTouchBegan(CCTouch* touch, CCEvent* event);
   virtual void ccTouchMoved(CCTouch* touch, CCEvent* event);
   virtual void ccTouchEnded(CCTouch* touch, CCEvent* event);
   virtual void registerWithTouchDispatcher();
 
   b2World* GetWorld() { return box2d_world_; }
 
@@ skipping 67 matching lines @@
   float box2d_restitution_;
   // Friction given to new physics objects
   float box2d_friction_;
 
   // The list of points currently being drawn by the user
   PointList points_being_drawn_;
 
   CCLuaStack* lua_stack_;
 };
 
-#endif  // PHYSICS_LAYER_H_
+#endif  // LEVEL_LAYER_H_