Move prerender histograms out of prerender manager.

chrome/browser/prerender/prerender_origin.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/prerender/prerender_origin.h"
 
 #include "base/metrics/histogram.h"
 #include "chrome/browser/prerender/prerender_manager.h"
 
 namespace prerender {
 
 namespace {
 
 const char* kOriginNames[] = {
   "Link Rel Prerender",
   "Omnibox",
+  "GWS Prerender",
   "Max"
 };
 COMPILE_ASSERT(arraysize(kOriginNames) == ORIGIN_MAX + 1,
                PrerenderOrigin_name_count_mismatch);
-
 }
 
 const char* NameFromOrigin(Origin origin) {
   DCHECK(static_cast<int>(origin) >= 0 &&
          origin <= ORIGIN_MAX);
   return kOriginNames[origin];
 }
 
 }  // namespace prerender