[Payments] Move journey logger to native.

components/payments/core/journey_logger.h

+// Copyright 2017 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 COMPONENTS_PAYMENTS_CORE_JOURNEY_LOGGER_H_
+#define COMPONENTS_PAYMENTS_CORE_JOURNEY_LOGGER_H_
+
+#include <string>
+
+#include "base/macros.h"
+
+namespace payments {
+
+// A class to keep track of different stats during a Payment Request journey. It
+// collects different metrics during the course of the checkout flow, like the
+// number of credit cards that the user added or edited. The metrics will be
+// logged when RecordJourneyStatsHistograms is called with the completion status
+// of the Payment Request.
+class JourneyLogger {
+ public:
+  // Note: These constants should always be in sync with their counterpart in
+  // JourneyLogger.java.

[please use gerrit instead, 2017/03/24 16:31:47]

Add a mirror comment in JourneyLogger.java. Use the full path in both comments.

[sebsg, 2017/03/24 18:37:47]

Done.

+  // The different sections of a Payment Request. Used to record journey
+  // stats.
+  enum Sections {

[please use gerrit instead, 2017/03/24 16:31:47]

Please use "enum class". Let's use singular "Section" similar to
"CompletionStatus" below, for example.

[sebsg, 2017/03/24 18:37:47]

Unfortunately they have to be implicitly convertible to int to be logged in
UMA...

+    SECTION_CONTACT_INFO = 0,
+    SECTION_CREDIT_CARDS = 1,
+    SECTION_SHIPPING_ADDRESS = 2,
+    SECTION_MAX,
+  };
+
+  // For the CanMakePayment histograms.
+  enum CanMakePaymentUsage {
+    CAN_MAKE_PAYMENT_USED = 0,
+    CAN_MAKE_PAYMENT_NOT_USED = 1,
+    CAN_MAKE_PAYMENT_USE_MAX,
+  };
+
+  // Used to log different parameters' effect on whether the transaction was
+  // completed.
+  enum CompletionStatus {
+    COMPLETION_STATUS_COMPLETED = 0,
+    COMPLETION_STATUS_ABORTED = 1,
+    COMPLETION_STATUS_MAX,
+  };
+
+  // Used to mesure the impact of the CanMakePayment return value on whether the
+  // Payment Request is shown to the user.
+  static const int CMP_SHOW_COULD_NOT_MAKE_PAYMENT_AND_DID_NOT_SHOW = 0;

[please use gerrit instead, 2017/03/24 16:31:47]

Let's use "enum class" here as well.

[sebsg, 2017/03/24 18:37:47]

I thought it was more clear this way. It allows stuff like

CMP_SHOW_DID_SHOW | CMP_SHOW_COULD_MAKE_PAYMENT

But if you really prefer it to be an enum, I can enumerate the values.

+  static const int CMP_SHOW_DID_SHOW = 1 << 0;
+  static const int CMP_SHOW_COULD_MAKE_PAYMENT_ = 1 << 1;
+  static const int CMP_SHOW_MAX = 4;
+
+  JourneyLogger();
+  ~JourneyLogger();
+
+  // Increments the number of selection adds for the specified section.
+  void IncrementSelectionAdds(int section);

[please use gerrit instead, 2017/03/24 16:31:47]

Use the enum type instead of int. Same below.

[sebsg, 2017/03/24 18:37:47]

Done.

+
+  // Increments the number of selection changes for the specified section.
+  void IncrementSelectionChanges(int section);
+
+  // Increments the number of selection edits for the specified section.
+  void IncrementSelectionEdits(int section);
+
+  // Sets the number of suggestions shown for the specified section.
+  void SetNumberOfSuggestionsShown(int section, int number);
+
+  // Records the fact that the merchant called CanMakePayment and records it's
+  // return value.
+  void SetCanMakePaymentValue(bool value);
+
+  // Records the fact that the Payment Request was shown to the user.
+  void SetShowCalled();
+
+  // Records the histograms for all the sections that were requested by the
+  // merchant and for the usage of the CanMakePayment method and its effect on
+  // the transaction. This method should be called when the Payment Request has
+  // either been completed or aborted.
+  void RecordJourneyStatsHistograms(const std::string& submission_type);

[please use gerrit instead, 2017/03/24 16:31:47]

Why not use an enum here as well?

[sebsg, 2017/03/24 18:37:47]

Done.

+
+ private:
+  static const int NUMBER_OF_SECTIONS = 3;
+
+  // The minimum expected value of CustomCountHistograms is always set to 1. It
+  // is still possible to log the value 0 to that type of histogram.

[please use gerrit instead, 2017/03/24 16:31:47]

Note about keeping this in sync with JourneyLogger.java.

[sebsg, 2017/03/24 18:37:47]

Done.

+  const int MIN_EXPECTED_SAMPLE = 1;
+  const int MAX_EXPECTED_SAMPLE = 49;
+  const int NUMBER_BUCKETS = 50;
+
+  struct SectionStats {
+    SectionStats()
+        : number_selection_adds_(0),
+          number_selection_changes_(0),
+          number_selection_edits_(0),
+          number_suggestions_shown_(0),
+          is_requested_(false) {}
+
+    int number_selection_adds_;
+    int number_selection_changes_;
+    int number_selection_edits_;
+    int number_suggestions_shown_;
+    int is_requested_;

[please use gerrit instead, 2017/03/24 16:31:47]

bool

[sebsg, 2017/03/24 18:37:47]

Done.

+  };
+
+  // Records the histograms for all the sections that were requested by the
+  // merchant.
+  void RecordSectionSpecificStats(const std::string& submission_type);
+
+  // Records the metrics related the the CanMakePayment method.
+  void RecordCanMakePaymentStats(CompletionStatus completion_status);
+
+  // Records CanMakePayment's return value effect on whether the Payment Request
+  // was shown or not.
+  void RecordCanMakePaymentEffectOnShow();
+
+  // Records the completion status depending on the the usage and return value
+  // of the CanMakePaymentMethod.
+  void RecordCanMakePaymentEffectOnCompletion(
+      CompletionStatus completion_status);
+
+  SectionStats sections_[NUMBER_OF_SECTIONS];
+  bool was_can_make_payments_used_;
+  bool could_make_payment_;
+  bool was_show_called_;
+
+  DISALLOW_COPY_AND_ASSIGN(JourneyLogger);
+};
+
+}  // namespace payments
+
+#endif  // COMPONENTS_PAYMENTS_CORE_JOURNEY_LOGGER_H_