Move Stats, histograms, and field trial into a metrics subdirectory of base and
put them in the base namespace.

TEST=it compiles
BUG=none

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@62510 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/chrome/browser/browser_main.h b/chrome/browser/browser_main.h
index 033fb1bd..9154a4c 100644
--- a/chrome/browser/browser_main.h
+++ b/chrome/browser/browser_main.h
@@ -7,7 +7,7 @@
 #pragma once
 
 #include "base/basictypes.h"
-#include "base/field_trial.h"
+#include "base/metrics/field_trial.h"
 #include "base/scoped_ptr.h"
 #include "base/tracked_objects.h"
 
@@ -140,7 +140,7 @@
 #endif
 
   // Statistical testing infrastructure for the entire browser.
-  FieldTrialList field_trial_;
+  base::FieldTrialList field_trial_;
 
   // Members initialized in |MainMessageLoopStart()| ---------------------------
   scoped_ptr<MessageLoop> main_message_loop_;