Consistently use namespaced base::Version in extensions code.

extensions/browser/updater/extension_downloader.cc

Index: extensions/browser/updater/extension_downloader.cc
diff --git a/extensions/browser/updater/extension_downloader.cc b/extensions/browser/updater/extension_downloader.cc
index 123fb307acb481a7c7bf88cd1fbbe2b4ebdbcad2..91c08c29e28972c55f7d8d82d540d3869fa3682f 100644
--- a/extensions/browser/updater/extension_downloader.cc
+++ b/extensions/browser/updater/extension_downloader.cc
@@ -151,9 +151,9 @@ bool IncrementAuthUserIndex(GURL* url) {
 
 }  // namespace
 
-UpdateDetails::UpdateDetails(const std::string& id, const Version& version)
-    : id(id), version(version) {
-}
+UpdateDetails::UpdateDetails(const std::string& id,
+                             const base::Version& version)
+    : id(id), version(version) {}
 
 UpdateDetails::~UpdateDetails() {
 }
@@ -228,7 +228,7 @@ bool ExtensionDownloader::AddPendingExtension(const std::string& id,
   // Use a zero version to ensure that a pending extension will always
   // be updated, and thus installed (assuming all extensions have
   // non-zero versions).
-  Version version("0.0.0.0");
+  base::Version version("0.0.0.0");
   DCHECK(version.IsValid());
 
   return AddExtensionData(id, version, Manifest::TYPE_UNKNOWN, update_url,
@@ -287,7 +287,7 @@ void ExtensionDownloader::set_test_delegate(
 }
 
 bool ExtensionDownloader::AddExtensionData(const std::string& id,
-                                           const Version& version,
+                                           const base::Version& version,
                                            Manifest::Type extension_type,
                                            const GURL& extension_update_url,
                                            const std::string& update_url_data,
@@ -632,8 +632,8 @@ void ExtensionDownloader::DetermineUpdates(
 
       VLOG(2) << id << " is at '" << version << "'";
 
-      Version existing_version(version);
-      Version update_version(update->version);
+      base::Version existing_version(version);
+      base::Version update_version(update->version);
       if (!update_version.IsValid() ||
           update_version.CompareTo(existing_version) <= 0) {
         continue;
@@ -850,7 +850,7 @@ void ExtensionDownloader::NotifyExtensionsDownloadFailed(
 
 void ExtensionDownloader::NotifyUpdateFound(const std::string& id,
                                             const std::string& version) {
-  UpdateDetails updateInfo(id, Version(version));
+  UpdateDetails updateInfo(id, base::Version(version));
   content::NotificationService::current()->Notify(
       extensions::NOTIFICATION_EXTENSION_UPDATE_FOUND,
       content::NotificationService::AllBrowserContextsAndSources(),