[Oilpan] Unify memory usage reporters of Oilpan

third_party/WebKit/Source/platform/MemoryUsageProvider.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 MemoryUsageProvider_h
+#define MemoryUsageProvider_h
+
+#include "public/platform/WebCommon.h"
+#include "public/platform/WebMemoryDumpProvider.h"
+#include "wtf/Allocator.h"
+#include "wtf/Noncopyable.h"
+
+namespace v8 {
+class Isolate;
+}

[haraken, 2016/02/04 12:00:29]

Nit: We normally just include <v8.h>.

[peria, 2016/02/08 08:41:10]

It is not visible from platform/heap/HeapPage.h, which includes this header
file.

+
+namespace blink {
+
+class MemoryUsageProvider {
+    USING_FAST_MALLOC(MemoryUsageProvider);
+    WTF_MAKE_NONCOPYABLE(MemoryUsageProvider);
+public:
+    static MemoryUsageProvider* instance();

[haraken, 2016/02/04 12:00:29]

Instead of making this class a singleton, it might be better to make
V8PerIsolateData own the MemoryUsageProvider.

V8PerIsolateData : v8::Isolate = 1 : 1.

[peria, 2016/02/08 08:41:10]

This method is expected to return thread specific instances.

+    MemoryUsageProvider();
+    ~MemoryUsageProvider();
+
+    void setIsolate(v8::Isolate* isolate) { m_isolate = isolate; }
+
+    void adjustAmountOfAllocatedMemory();
+
+private:
+
+    v8::Isolate* m_isolate;
+    int64_t m_previousSize;
+};
+
+} // namespace blink
+
+#endif // PartitionAllocMemoryDumpProvider_h