metrics/base: log whether drives have seek penalties.

chrome/browser/metrics/drive_metrics_provider.h

+// Copyright 2015 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_METRICS_DRIVE_METRICS_PROVIDER_H_
+#define CHROME_BROWSER_METRICS_DRIVE_METRICS_PROVIDER_H_
+
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "base/threading/thread_checker.h"
+#include "components/metrics/metrics_provider.h"
+
+// Provides metrics about the local drives on a user's computer. Currently only
+// checks to see if they incur a seek-time penalty (e.g. if they're SSDs).
+//
+// Defers gathering metrics until after "rush hour" (startup) so as to not bog
+// down the FILE thread.
+class DriveMetricsProvider : public metrics::MetricsProvider {
+ public:
+  DriveMetricsProvider();
+  ~DriveMetricsProvider() override;
+
+  // metrics::MetricsDataProvider:
+  void ProvideSystemProfileMetrics(
+      metrics::SystemProfileProto* system_profile_proto) override;
+
+  struct SeekPenaltyResponse {

[Alexei Svitkine (slow), 2015/03/16 16:49:36]

Move these to the private section.

[Dan Beam, 2015/03/16 19:20:23]

they were used in the anonymous namespace, so had to be public.  moved to
private: and changed anon namespace funcs to private static/instance methods.

+    SeekPenaltyResponse();
+    bool success;
+    bool has_seek_penalty;
+  };
+
+  struct DriveMetrics {
+    SeekPenaltyResponse app_drive;
+    SeekPenaltyResponse user_data_drive;
+  };
+
+ private:
+  // Called when metrics are done being gathered from the FILE thread.
+  void GotDriveMetrics(const DriveMetrics& metrics);
+
+  // False until |GotDriveMetrics| is called.
+  bool got_metrics_;
+  DriveMetrics metrics_;
+
+  base::ThreadChecker thread_checker_;
+  base::WeakPtrFactory<DriveMetricsProvider> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(DriveMetricsProvider);
+};
+
+#endif  // CHROME_BROWSER_METRICS_DRIVE_METRICS_PROVIDER_H_