Integrate Crashpad UMA

base/metrics/persistent_metrics_file_util.cc

+// 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.
+
+#include "base/metrics/persistent_metrics_file_util.h"
+
+#include "base/files/file_path.h"
+#include "base/files/file_util.h"
+#include "base/metrics/persistent_histogram_allocator.h"
+#include "base/metrics/persistent_memory_allocator.h"
+
+namespace base {
+
+void InitializeGlobalPersistentMetricsStorage(const base::FilePath& dir,
+                                              const char* metrics_name,
+                                              size_t size) {
+  // Metrics maps one file that we're going to use during this run (the
+  // "-active" one), and provides the previous one to the metrics system for for
+  // association with the previous run. On startup, we move the current -active
+  // to the base name, and then start this session on the -active one. Normally,
+  // when the browser starts it will read and delete the base name one, but in
+  // the case that something goes wrong, we will overwrite/delete any old one.
+  base::FilePath metrics_file =
+      dir.AppendASCII(metrics_name)
+          .AddExtension(PersistentMemoryAllocator::kFileExtension);
+  base::FilePath active_file =
+      dir.AppendASCII(metrics_name + std::string("-active"))
+          .AddExtension(PersistentMemoryAllocator::kFileExtension);
+
+  if (!base::ReplaceFile(active_file, metrics_file, nullptr))
+    base::DeleteFile(metrics_file, /*recursive=*/false);
+
+  base::GlobalHistogramAllocator::CreateWithFile(active_file, size, 0,
+                                                 metrics_name);
+
+  // Get the allocator that was just created and report result. Exit if the
+  // allocator could not be created.
+  base::GlobalHistogramAllocator* allocator =
+      base::GlobalHistogramAllocator::Get();
+  if (!allocator)
+    return;
+
+  // Create tracking histograms for the allocator and record storage file.
+  allocator->CreateTrackingHistograms(metrics_name);

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

This is the only line cannot be moved into CreateWithActiveFile() as it isn't
always the creating process that manages those histograms but at least it's only
one external line of code.

Feel free change the CreateWith*() methods to return true/false indicating
success.  That'll simplify the "did it work" check before calling
CreateTrackingHitograms().

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

Done.

+  allocator->SetPersistentLocation(active_file);

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

I think this could be part of CreateWithFile().

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

Done. I removed it from chrome/browser/chrome_browser_field_trials.cc too, which
looks like a slight behaviour change (for the "LocalMemory" case) but that
seemed like it probably had no effect anyway (?).

+}
+
+void CleanUpGlobalPersistentHistogramStorage() {
+  base::GlobalHistogramAllocator* allocator =
+      base::GlobalHistogramAllocator::Get();
+  if (!allocator)
+    return;
+
+  const base::FilePath& path = allocator->GetPersistentLocation();
+  if (path.empty())
+    return;
+
+  // Open (with delete) and then immediately close the file by going out of
+  // scope. This is the only cross-platform safe way to delete a file that may
+  // be open elsewhere. Open handles will continue to operate normally but
+  // new opens will not be possible.
+  base::File file(path, base::File::FLAG_OPEN | base::File::FLAG_READ |
+                            base::File::FLAG_DELETE_ON_CLOSE);
+}
+
+}  // namespace base