Persist setup metrics and have Chrome report them during UMA upload.

chrome/installer/setup/installer_metrics.h

Index: chrome/installer/setup/installer_metrics.h
diff --git a/chrome/installer/setup/installer_metrics.h b/chrome/installer/setup/installer_metrics.h
new file mode 100644
index 0000000000000000000000000000000000000000..80d3e24cfcbca8a33b1fd0d503fc68f2dc2a9383
--- /dev/null
+++ b/chrome/installer/setup/installer_metrics.h
@@ -0,0 +1,25 @@
+// Copyright (c) 2016 The Chromium Authors. All rights reserved.

[grt (UTC plus 2), 2016/02/08 18:09:19]

nit: no (c) in copyright notices for new files
(http://www.chromium.org/developers/coding-style#TOC-File-headers)

[bcwhite, 2016/02/09 21:08:46]

Done.

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_INSTALLER_SETUP_INSTALLER_METRICS_H_
+#define CHROME_INSTALLER_SETUP_INSTALLER_METRICS_H_
+
+namespace base {
+class FilePath;
+}  // namespace base
+
+namespace installer {
+
+// Create a persistent space for any histograms that can be reported later

[grt (UTC plus 2), 2016/02/08 18:09:19]

nit: "Creates..." as per
https://google.github.io/styleguide/cppguide.html#Function_Comments

[bcwhite, 2016/02/09 21:08:46]

Done.

+// by the browser process.
+void BeginPersistentHistogramStorage(const char* name);
+
+// Save all the persistent histograms to a single file on disk for reading

[grt (UTC plus 2), 2016/02/08 18:09:19]

nit: "Saves..."

[bcwhite, 2016/02/09 21:08:46]

Done.

+// by the browser so it can be reported.
+void EndPersistentHistogramStorage(const base::FilePath& target_dir);
+
+}  // namespace installer
+
+#endif  // CHROME_INSTALLER_SETUP_INSTALLER_METRICS_H_
+