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..d84364085d519e0bd3824dc58cbec26a28a4984b
--- /dev/null
+++ b/chrome/installer/setup/installer_metrics.h
@@ -0,0 +1,29 @@
+// 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_INSTALLER_SETUP_INSTALLER_METRICS_H_
+#define CHROME_INSTALLER_SETUP_INSTALLER_METRICS_H_
+
+namespace base {
+class FilePath;
+}  // namespace base
+
+namespace installer {
+
+// Creates a persistent space for any histograms that can be reported later
+// by the browser process. It should be called as early as possible in the
+// process lifetime and never called again.
+void BeginPersistentHistogramStorage();
+
+// Saves all the persistent histograms to a single file on disk for reading
+// by the browser so it can be reported. It is generally called once during
+// process exit. Multiple calls to this are possible if "snapshots" are
+// desired; they are cumulative in what is saved, not just what has changed
+// since the previous call.
+void EndPersistentHistogramStorage(const base::FilePath& target_dir);
+
+}  // namespace installer
+
+#endif  // CHROME_INSTALLER_SETUP_INSTALLER_METRICS_H_
+