FBTF: Forward declare and move constructors in chrome/common/extensions/.

chrome/common/extensions/extension_unpacker.h

Index: chrome/common/extensions/extension_unpacker.h
diff --git a/chrome/common/extensions/extension_unpacker.h b/chrome/common/extensions/extension_unpacker.h
index ebe29156988098790878b3d7261aef5546e873c5..6883597b536813c044578ccb044f60c35b666101 100644
--- a/chrome/common/extensions/extension_unpacker.h
+++ b/chrome/common/extensions/extension_unpacker.h
@@ -24,8 +24,8 @@ class ExtensionUnpacker {
  public:
   typedef std::vector< Tuple2<SkBitmap, FilePath> > DecodedImages;
 
-  explicit ExtensionUnpacker(const FilePath& extension_path)
-      : extension_path_(extension_path) {}
+  explicit ExtensionUnpacker(const FilePath& extension_path);
+  ~ExtensionUnpacker();
 
   // Install the extension file at |extension_path|.  Returns true on success.
   // Otherwise, error_message will contain a string explaining what went wrong.