Always persist histograms from setup.exe.

chrome/installer/setup/persistent_histogram_storage.h

 // Copyright 2016 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_COMMON_ORIGIN_TRIALS_CHROME_ORIGIN_TRIAL_POLICY_H_
-#define CHROME_COMMON_ORIGIN_TRIALS_CHROME_ORIGIN_TRIAL_POLICY_H_
+#ifndef CHROME_INSTALLER_SETUP_PERSISTENT_HISTOGRAM_STORAGE_H_
+#define CHROME_INSTALLER_SETUP_PERSISTENT_HISTOGRAM_STORAGE_H_
 
-#include <set>
-#include <string>
+#include "base/files/file_path.h"
+#include "base/macros.h"
 
-#include "base/macros.h"
-#include "base/strings/string_piece.h"
-#include "content/public/common/origin_trial_policy.h"
+namespace installer {
 
-// This class is instantiated on the main/ui thread, but its methods can be
-// accessed from any thread.
-class ChromeOriginTrialPolicy : public content::OriginTrialPolicy {
+// When a PersistentHistogramStorage is destructed, histograms recorded during
+// its lifetime are persisted in the directory set by set_storage_dir().
+// Histograms are not persisted if set_storage_dir() has not been called or if
+// the storage directory does not exist on destruction.
+// PersistentHistogramStorage should be instantiated as early as possible in the
+// process lifetime and should never be instantiated again. Persisted histograms
+// will eventually be reported by the browser process.
+class PersistentHistogramStorage {
  public:
-  ChromeOriginTrialPolicy();
-  ~ChromeOriginTrialPolicy() override;
+  PersistentHistogramStorage();
+  ~PersistentHistogramStorage();
 
-  // OriginTrialPolicy interface
-  base::StringPiece GetPublicKey() const override;
-  bool IsFeatureDisabled(base::StringPiece feature) const override;
+  // Sets |storage_dir| as the directory in which histograms will be persisted
+  // when this PersistentHistogramStorage is destructed.
+  void set_storage_dir(const base::FilePath& storage_dir) {

[bcwhite, 2016/09/13 19:53:53]

You have set_storage_dir and GetStorageDir, only one of which is static.  Please
be consistent (or completely, rather than partially, inconsistent).

[fdoray, 2016/09/13 20:18:25]

Done.

+    storage_dir_ = storage_dir;
+  }
 
-  bool SetPublicKeyFromASCIIString(const std::string& ascii_public_key);
-  bool SetDisabledFeatures(const std::string& disabled_feature_list);
+  // Returns a directory from which a product installed in |target_path| reports
+  // persisted histograms. Should be used as an argument to set_storage_dir().
+  static base::FilePath GetStorageDir(const base::FilePath& target_path);
 
  private:
-  std::string public_key_;
-  std::set<std::string> disabled_features_;
+  base::FilePath storage_dir_;
 
-  DISALLOW_COPY_AND_ASSIGN(ChromeOriginTrialPolicy);
+  DISALLOW_COPY_AND_ASSIGN(PersistentHistogramStorage);
 };
 
-#endif  // CHROME_COMMON_ORIGIN_TRIALS_CHROME_ORIGIN_TRIAL_POLICY_H_
+}  // namespace installer
+
+#endif  // CHROME_INSTALLER_SETUP_PERSISTENT_HISTOGRAM_STORAGE_H_