Move Version to base namespace.

base/version.h

Index: base/version.h
diff --git a/base/version.h b/base/version.h
index ab7145e16d0b53de0c54d8433b6b50ceed4f6fa7..b3012eb921b1e62a803b681f03954fbb17d14cea 100644
--- a/base/version.h
+++ b/base/version.h
@@ -11,6 +11,8 @@
 #include "base/base_export.h"
 #include "base/basictypes.h"
 
+namespace base {
+
 // Version represents a dotted version number, like "1.2.3.4", supporting
 // parsing and comparison.
 class BASE_EXPORT Version {
@@ -61,4 +63,10 @@ class BASE_EXPORT Version {
   std::vector<uint16> components_;
 };
 
+}  // namespace base
+
+// TODO(xhwang) remove this when all users are updated to explicitly use the
+// namespace
+using base::Version;
+
 #endif  // BASE_VERSION_H_