Integrate Crashpad UMA

base/metrics/persistent_metrics_file_util.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 BASE_METRICS_PERSISTENT_METRICS_FILE_UTIL_H_

[bcwhite, 2016/09/14 13:16:12]

Don't we have some policy against "*_util" files?

You could put this as CreateWithActiveFile(base_path, active_path, size, id,
name) under GlobalHistogramAllocator in persistent_histogram_allocator.{h,cc}. 
An addition CreateWithActiveFile(dir, size, id, name) that calls the former with
constructed paths would also be useful.

A ConstructFilePaths(dir, name, out_base_path, out_active_path) would also
simplify the code both here and during registration.  It would concatenate
everything and add the standard extension.  Pass nullptr for out_* if not
interested in that path.

[scottmg, 2016/09/14 20:37:01]

Done, much better! It'll be slightly more to stub in mini_chromium, but should
be fine.

+#define BASE_METRICS_PERSISTENT_METRICS_FILE_UTIL_H_
+
+#include "base/base_export.h"
+
+namespace base {
+
+class FilePath;
+
+// Initializes a pair of metrics files in the given directory, using
+// |metrics_name| as the basename of the previous run file, and basename +
+// "-active" for the current run, with the given size. The basename one should
+// be associated with the previous run when registered with the metrics system,
+// and the "-active" with the current run.
+BASE_EXPORT void InitializeGlobalPersistentMetricsStorage(
+    const base::FilePath& dir,
+    const char* metrics_name,
+    size_t size);
+
+// If there is a global metrics file being updated on disk, mark it to be
+// deleted when the process exits. A normal shutdown is almost complete
+// so there is no benefit in keeping a file with no new data to be processed
+// during the next startup sequence. Deleting the file during shutdown adds
+// an extra disk-access or two to shutdown but eliminates the unnecessary
+// processing of the contents during startup only to find nothing.
+BASE_EXPORT void CleanUpGlobalPersistentHistogramStorage();

[bcwhite, 2016/09/14 13:16:12]

There's a WriteToPersistentLocation() in that class so perhaps
DeletePersistentLocation() would be fitting.

[scottmg, 2016/09/14 20:37:01]

Done.

+
+}  // namespace base
+
+#endif  // BASE_METRICS_PERSISTENT_METRICS_FILE_UTIL_H_