Revert "Update all users of base::Version to explicitly specify the namespace, and clean up the hea…

extensions/common/extension.cc

Index: extensions/common/extension.cc
diff --git a/extensions/common/extension.cc b/extensions/common/extension.cc
index ceb6a79a32beafaf066768cacb687d04518dc630..d3bb5a78fadfb0a5a87487fa52aa4b744f84b492 100644
--- a/extensions/common/extension.cc
+++ b/extensions/common/extension.cc
@@ -590,7 +590,7 @@ bool Extension::LoadVersion(base::string16* error) {
     *error = base::ASCIIToUTF16(errors::kInvalidVersion);
     return false;
   }
-  version_.reset(new base::Version(version_str));
+  version_.reset(new Version(version_str));
   if (!version_->IsValid() || version_->components().size() > 4) {
     *error = base::ASCIIToUTF16(errors::kInvalidVersion);
     return false;