Revert of base: Remove using:: declaration from version.h header.

chrome/installer/setup/install.h

Index: chrome/installer/setup/install.h
diff --git a/chrome/installer/setup/install.h b/chrome/installer/setup/install.h
index a2c9b55e5312c39830dd6fc6f5fb58434bb36214..5eac8e21d5b4d2ae1fe97f4fc84158001944c736 100644
--- a/chrome/installer/setup/install.h
+++ b/chrome/installer/setup/install.h
@@ -59,7 +59,7 @@
 // |src_path|\VisualElements exists.
 // Returns true unless the manifest is supposed to be created, but fails to be.
 bool CreateVisualElementsManifest(const base::FilePath& src_path,
-                                  const base::Version& version);
+                                  const Version& version);
 
 // Overwrites shortcuts (desktop, quick launch, and start menu) if they are
 // present on the system.
@@ -115,7 +115,7 @@
     const base::FilePath& src_path,
     const base::FilePath& prefs_path,
     const installer::MasterPreferences& prefs,
-    const base::Version& new_version);
+    const Version& new_version);
 
 // Performs installation-related tasks following an OS upgrade.
 // |chrome| The installed product (must be a browser).