Emit UMAs for metrics from memory instrumentation service.

chrome/browser/metrics/process_memory_metrics_emitter.h

+// Copyright 2017 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_BROWSER_METRICS_PROCESS_MEMORY_METRICS_EMITTER_H_
+#define CHROME_BROWSER_METRICS_PROCESS_MEMORY_METRICS_EMITTER_H_
+
+#include "base/memory/ref_counted.h"
+#include "services/resource_coordinator/public/interfaces/memory/memory_instrumentation.mojom.h"
+
+// This class asynchronously fetches memory metrics for each process, and then
+// emits UMA metrics from those metrics.
+// Each instance is self-owned, and will delete itself once it has finished
+// emitting metrics.
+// This class is an analog to MetricsMemoryDetails, but uses the resource
+// coordinator service to fetch data, rather than doing all the processing
+// manually.
+class ProcessMemoryMetricsEmitter
+    : public base::RefCountedThreadSafe<ProcessMemoryMetricsEmitter> {
+ public:
+  ProcessMemoryMetricsEmitter();
+
+  // This must be called on the main thread of the browser process.
+  void FetchAndEmitProcessMemoryMetrics();
+
+ protected:
+  virtual ~ProcessMemoryMetricsEmitter();
+
+  // Virtual for testing.
+  virtual void ReceivedMemoryDump(
+      uint64_t dump_guid,
+      bool success,
+      memory_instrumentation::mojom::GlobalMemoryDumpPtr ptr);
+
+ private:
+  friend class base::RefCountedThreadSafe<ProcessMemoryMetricsEmitter>;
+
+  memory_instrumentation::mojom::CoordinatorPtr coordinator_;
+
+  DISALLOW_COPY_AND_ASSIGN(ProcessMemoryMetricsEmitter);
+};
+
+#endif  // CHROME_BROWSER_METRICS_PROCESS_MEMORY_METRICS_EMITTER_H_