Upstream Chrome on iOS source code [2/11].

ios/chrome/browser/metrics/first_user_action_recorder.h

+// Copyright 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 IOS_CHROME_BROWSER_METRICS_FIRST_USER_ACTION_RECORDER_H_
+#define IOS_CHROME_BROWSER_METRICS_FIRST_USER_ACTION_RECORDER_H_
+
+#include <vector>
+
+#include "base/metrics/user_metrics.h"
+#include "base/time/time.h"
+
+// Histogram names (visible for testing only).
+// Each is a 2-element array where the first element is the
+// name of the histogram for handsets and the second is the name of the
+// histogram for tablets.
+
+// The histogram to plot background duration before 'new task' actions.
+extern const char* kFirstUserActionNewTaskHistogramName[];
+
+// The histogram to plot background duration before 'continuation' actions.
+extern const char* kFirstUserActionContinuationHistogramName[];
+
+// The histogram to plot background duration before 'expiration' actions.
+extern const char* kFirstUserActionExpirationHistogramName[];
+
+// The name of the histogram to plot the type of first user action (see
+// |FirstUserActionType|).
+extern const char* kFirstUserActionTypeHistogramName[];
+
+// Since it logs user actions while it exists, it should only be instantiated
+// while metrics recording is enabled.
+class FirstUserActionRecorder {
+ public:
+  // Indicies of the histogram name arrays for each device family.
+  enum DeviceFamilyIndex { HANDSET = 0, TABLET = 1 };
+
+  // Values of the first user action type histogram.
+  enum FirstUserActionType {
+    NEW_TASK = 0,
+    CONTINUATION,
+    EXPIRATION,
+    START_ON_NTP,
+    FIRST_USER_ACTION_TYPE_COUNT,
+  };
+
+  explicit FirstUserActionRecorder(base::TimeDelta background_duration);
+  virtual ~FirstUserActionRecorder();
+
+  // Records that no applicable user action occurred.
+  void Expire();
+
+  // Records that the app started with the NTP active.
+  void RecordStartOnNTP();
+
+ private:
+  // Records metrics if |action_name| indicates the start of a new task or the
+  // continuation of an existing task.
+  void OnUserAction(const std::string& action_name);
+
+  // Records the appropriate metrics for the given action type.
+  void RecordAction(const FirstUserActionType& action_type,
+                    const std::string& log_message);
+
+  // Returns true if the specified action should be processed, or false if the
+  // action should be ignored.
+  bool ShouldProcessAction(const std::string& action_name);
+
+  // Returns true if the given array contains the given string.
+  bool ArrayContainsString(const char* to_search[],
+                           const size_t to_search_size,
+                           const char* to_find);
+
+  // True if running on a tablet.
+  const DeviceFamilyIndex device_family_;
+
+  // True if this instance has recorded a 'new task' or 'continuation task'
+  // metric.
+  bool recorded_action_;
+
+  // True if this instance has rethrown an action.
+  bool action_pending_;
+
+  // The amount of time the app was in the background before this recorder was
+  // created.
+  base::TimeDelta background_duration_;
+
+  // The callback to invoke when an action is recorded.
+  base::ActionCallback action_callback_;
+
+  DISALLOW_COPY_AND_ASSIGN(FirstUserActionRecorder);
+};
+
+#endif  // IOS_CHROME_BROWSER_METRICS_FIRST_USER_ACTION_RECORDER_H_