[Tentaive patch for discussion] Add Purge+Suspend metrics as UMA.

third_party/WebKit/public/web/WebMemoryStatistics.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 WebMemoryStatistics_h
+#define WebMemoryStatistics_h
+
+#include "public/platform/WebCommon.h"
+
+namespace blink {
+
+struct WebMemoryStatistics {
+    size_t partitionAllocTotalAllocatedBytes;
+    size_t partitionAllocTotalBytes;
+    size_t blinkGCTotalBytes;
+    size_t blinkGCTotalAllocatedBytes;
+
+    WebMemoryStatistics()
+        : partitionAllocTotalAllocatedBytes(0)
+        , partitionAllocTotalBytes(0)
+        , blinkGCTotalBytes(0)
+        , blinkGCTotalAllocatedBytes(0)
+    {
+    }
+
+    BLINK_EXPORT static WebMemoryStatistics Get();
+};
+
+} // namespace blink
+
+#endif