Put VariationsService into the chrome_variations namespace.

Also, rename chrome_variations::ID to chrome_variations::VariationID,
since there are other things in that namespace now (which was already
the case with the protobuf classes).

BUG=none
TEST=compiles

Review URL: https://chromiumcodereview.appspot.com/10693106

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@145608 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/chrome/browser/prefs/browser_prefs.cc b/chrome/browser/prefs/browser_prefs.cc
index db1be73..2a851c1 100644
--- a/chrome/browser/prefs/browser_prefs.cc
+++ b/chrome/browser/prefs/browser_prefs.cc
@@ -125,7 +125,7 @@
   ProfileManager::RegisterPrefs(local_state);
   SigninManagerFactory::RegisterPrefs(local_state);
   SSLConfigServiceManager::RegisterPrefs(local_state);
-  VariationsService::RegisterPrefs(local_state);
+  chrome_variations::VariationsService::RegisterPrefs(local_state);
   WebCacheManager::RegisterPrefs(local_state);
 
 #if defined(ENABLE_CONFIGURATION_POLICY)