Add UMA histograms for policy loading.

chrome/browser/policy/policy_load_status.h

Index: chrome/browser/policy/policy_load_status.h
diff --git a/chrome/browser/policy/policy_load_status.h b/chrome/browser/policy/policy_load_status.h
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+// Copyright (c) 2013 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.
+
+#ifndef CHROME_BROWSER_POLICY_POLICY_LOAD_STATUS_H_
+#define CHROME_BROWSER_POLICY_POLICY_LOAD_STATUS_H_
+
+#include <bitset>
+
+#include "base/basictypes.h"
+
+namespace base {
+class HistogramBase;
+}
+
+namespace policy {
+
+// UMA histogram enum for policy load status. Don't change existing constants,
+// append additional constants to the end if needed.
+enum PolicyLoadStatus {
+  // Policy load attempt started. This gets logged for each policy load attempt
+  // to get a baseline on the number of requests, and an arbitrary number of
+  // the below status codes may get added in addition.
+  POLICY_LOAD_STATUS_STARTED,
+  // System failed to determine whether there's policy.
+  POLICY_LOAD_STATUS_QUERY_FAILED,
+  // No policy present.
+  POLICY_LOAD_STATUS_NO_POLICY,
+  // Data inaccessible, such as non-local policy file.
+  POLICY_LOAD_STATUS_INACCCESSIBLE,
+  // Data missing, such as policy file not present.
+  POLICY_LOAD_STATUS_MISSING,
+  // Trying with Wow64 redirection disabled.
+  POLICY_LOAD_STATUS_WOW64_REDIRECTION_DISABLED,
+  // Data read error, for example file reading errors.
+  POLICY_LOAD_STATUS_READ_ERROR,
+  // Data too large to process.
+  POLICY_LOAD_STATUS_TOO_BIG,
+  // Parse error.
+  POLICY_LOAD_STATUS_PARSE_ERROR,
+
+  // This must stay last.
+  POLICY_LOAD_STATUS_SIZE
+};
+
+// A helper for generating policy load status UMA statistics that'll collect
+// histogram samples for a policy load operation and records histogram samples
+// for the status codes that were seen on destruction.
+class PolicyLoadStatusSample {
+ public:
+  PolicyLoadStatusSample();
+  ~PolicyLoadStatusSample();
+
+  // Adds a status code.
+  void Add(PolicyLoadStatus status);
+
+ private:
+  std::bitset<POLICY_LOAD_STATUS_SIZE> status_bits_;
+  base::HistogramBase* histogram_;
+
+  DISALLOW_COPY_AND_ASSIGN(PolicyLoadStatusSample);
+};
+
+}  // namespace policy
+
+#endif  // CHROME_BROWSER_POLICY_POLICY_LOAD_STATUS_H_