Remove obviously unneeded forward declarations from headers under src/{app,base,net}.

base/file_version_info_mac.h

-// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
+// Copyright (c) 2010 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 BASE_FILE_VERSION_INFO_MAC_H_
 #define BASE_FILE_VERSION_INFO_MAC_H_
 #pragma once
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/file_version_info.h"
 #include "base/scoped_ptr.h"
 
 #ifdef __OBJC__
 @class NSBundle;
 #else
 class NSBundle;
 #endif
 
-class FilePath;
-
 // Provides a way to access the version information for a file.
 // This is the information you access when you select a file in the Windows
 // explorer, right-click select Properties, then click the Version tab.
 
 class FileVersionInfoMac : public FileVersionInfo {
  public:
   explicit FileVersionInfoMac(NSBundle *bundle);
   ~FileVersionInfoMac();
 
   // Accessors to the different version properties.
@@ skipping 22 matching lines @@
   // Similar to GetValue but returns a wstring (empty string if the property
   // does not exist).
   std::wstring GetStringValue(const wchar_t* name);
 
   NSBundle *bundle_;
 
   DISALLOW_COPY_AND_ASSIGN(FileVersionInfoMac);
 };
 
 #endif  // BASE_FILE_VERSION_INFO_MAC_H_