Cleanup: Remove unneeded forward declarations in ppapi.

ppapi/proxy/host_dispatcher.h

 // 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.
 
 #ifndef PPAPI_PROXY_HOST_DISPATCHER_H_
 #define PPAPI_PROXY_HOST_DISPATCHER_H_
 
 #include <map>
 #include <string>
 #include <vector>
 
 #include "base/memory/scoped_ptr.h"
 #include "base/process.h"
 #include "ppapi/c/pp_instance.h"
 #include "ppapi/proxy/dispatcher.h"
 #include "ppapi/shared_impl/function_group_base.h"
 
 struct PPB_Proxy_Private;
 struct PPB_Var_Deprecated;
 
-namespace base {
-class WaitableEvent;
-}
-
-namespace IPC {
-class SyncChannel;
-}
-
 namespace ppapi {
 
 struct Preferences;
 
 namespace proxy {
 
-class VarSerialization;
-
 class PPAPI_PROXY_EXPORT HostDispatcher : public Dispatcher {
  public:
   // Constructor for the renderer side.
   //
   // You must call InitHostWithChannel after the constructor.
   HostDispatcher(base::ProcessHandle host_process_handle,
                  PP_Module module,
                  GetInterfaceFunc local_get_interface);
   ~HostDispatcher();
 
@@ skipping 70 matching lines @@
 };
 
 // Create this object on the stack to prevent the module (and hence the
 // dispatcher) from being deleted out from under you. This is necessary when
 // calling some scripting functions that may delete the plugin.
 //
 // This may only be called in the host. The parameter is a plain Dispatcher
 // since that's what most callers have.
 class ScopedModuleReference {
  public:
-  ScopedModuleReference(Dispatcher* dispatcher);
+  explicit ScopedModuleReference(Dispatcher* dispatcher);
   ~ScopedModuleReference();
 
  private:
   HostDispatcher* dispatcher_;
 
   DISALLOW_COPY_AND_ASSIGN(ScopedModuleReference);
 };
 
 }  // namespace proxy
 }  // namespace ppapi
 
 #endif  // PPAPI_PROXY_HOST_DISPATCHER_H_