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

extensions/common/update_manifest.cc

Index: extensions/common/update_manifest.cc
diff --git a/extensions/common/update_manifest.cc b/extensions/common/update_manifest.cc
index 57162da71e7bc0d82a98040a4bc45ce9e4d0ffdf..20a55914526f7e41124a2a67712546b2ac7585cc 100644
--- a/extensions/common/update_manifest.cc
+++ b/extensions/common/update_manifest.cc
@@ -167,7 +167,7 @@ static bool ParseSingleAppTag(xmlNode* app_node, xmlNs* xml_namespace,
     *error_detail = "Missing version for updatecheck.";
     return false;
   }
-  Version version(result->version);
+  base::Version version(result->version);
   if (!version.IsValid()) {
     *error_detail = "Invalid version: '";
     *error_detail += result->version;
@@ -178,7 +178,7 @@ static bool ParseSingleAppTag(xmlNode* app_node, xmlNs* xml_namespace,
   // Get the minimum browser version (not required).
   result->browser_min_version = GetAttribute(updatecheck, "prodversionmin");
   if (result->browser_min_version.length()) {
-    Version browser_min_version(result->browser_min_version);
+    base::Version browser_min_version(result->browser_min_version);
     if (!browser_min_version.IsValid()) {
       *error_detail = "Invalid prodversionmin: '";
       *error_detail += result->browser_min_version;