Added prerendering to omnibox.

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",
+  "Pending Link Rel Prerender",
+  "Omnibox",
+  "Max"
+};
+COMPILE_ASSERT(arraysize(kOriginNames) == ORIGIN_MAX + 1,
+               PrerenderOrigin_name_count_mismatch);
+
+}
+
+void RecordOrigin(Origin origin) {

[cbentzel, 2011/06/22 17:27:32]

Why do we need to record this? We have all the data we need from the FinalStatus
histograms. 

[dominich, 2011/06/22 19:00:51]

It is calculable from FinalStatus but this is a quicker source for the data.

[cbentzel, 2011/06/22 19:08:40]

It's pretty easy to calculate from FinalStauts. I'd prefer to just have one
histograms to prevent chance of skew in the numbers due to forgetting to update
this location.

+  CHECK(origin < ORIGIN_MAX);
+  // FINAL_STATUS_CONTROL_GROUP indicates that the PrerenderContents
+  // was created only to measure "would-have-been-prerendered" for
+  // control group measurements. Don't pollute data with it.
+  if (PrerenderManager::IsControlGroup())
+    return;
+  UMA_HISTOGRAM_ENUMERATION("Prerender.Origin",
+                            origin,
+                            ORIGIN_MAX);
+}
+
+const char* NameFromOrigin(Origin origin) {

[cbentzel, 2011/06/22 17:27:32]

Is this being used?

[dominich, 2011/06/22 19:00:51]

Not currently, but I was going to add the info to the net-internals prerender
tab.

[cbentzel, 2011/06/22 19:08:40]

OK, I'm fine with it if there is a plan for it's use. 

+  DCHECK(static_cast<int>(origin) >= 0 &&
+         origin <= ORIGIN_MAX);
+  return kOriginNames[origin];
+}
+
+}  // namespace prerender