Add Web Resources usage to chrome://tracing.

third_party/WebKit/Source/core/fetch/WebCacheMemoryDumpProvider.h

Index: third_party/WebKit/Source/core/fetch/WebCacheMemoryDumpProvider.h
diff --git a/third_party/WebKit/Source/core/fetch/WebCacheMemoryDumpProvider.h b/third_party/WebKit/Source/core/fetch/WebCacheMemoryDumpProvider.h
new file mode 100644
index 0000000000000000000000000000000000000000..ba0994f2bd5479f13b30e41b8c24ba5171459230
--- /dev/null
+++ b/third_party/WebKit/Source/core/fetch/WebCacheMemoryDumpProvider.h
@@ -0,0 +1,41 @@
+// Copyright 2015 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 WebCacheMemoryDumpProvider_h
+#define WebCacheMemoryDumpProvider_h
+
+#include "core/fetch/MemoryCache.h"
+#include "platform/heap/Handle.h"
+#include "public/platform/WebCommon.h"
+#include "public/platform/WebMemoryDumpProvider.h"
+#include "wtf/MainThread.h"
+
+namespace blink {
+
+// This class is wrapper around MemoryCache to take memory snapshots. It dumps
+// the stats of cache only after the cache is created.
+class CORE_EXPORT WebCacheMemoryDumpProvider final : public WebMemoryDumpProvider {
+public:
+    // This class is singleton since there is a global MemoryCache object.
+    static WebCacheMemoryDumpProvider* instance();
+    ~WebCacheMemoryDumpProvider() override;
+
+    // WebMemoryDumpProvider implementation.
+    bool onMemoryDump(WebMemoryDumpLevelOfDetail, WebProcessMemoryDump*) override;
+
+    void setMemoryCache(MemoryCache* memoryCache)
+    {
+        ASSERT(isMainThread());
+        m_memoryCache = memoryCache;
+    }
+
+private:
+    WebCacheMemoryDumpProvider();
+
+    WeakPersistent<MemoryCache> m_memoryCache;
+};
+
+} // namespace blink
+
+#endif // WebCacheMemoryDumpProvider_h