[tracing] Add WebCache memory usage in Blink to chrome://tracing

components/web_cache/renderer/web_cache_memory_dump_provider.h

Index: components/web_cache/renderer/web_cache_memory_dump_provider.h
diff --git a/components/web_cache/renderer/web_cache_memory_dump_provider.h b/components/web_cache/renderer/web_cache_memory_dump_provider.h
new file mode 100644
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+++ b/components/web_cache/renderer/web_cache_memory_dump_provider.h
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+// 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 COMPONENTS_WEB_CACHE_RENDERER_WEB_CACHE_MEMORY_DUMP_PROVIDER_H
+#define COMPONENTS_WEB_CACHE_RENDERER_WEB_CACHE_MEMORY_DUMP_PROVIDER_H
+
+#include "base/lazy_instance.h"
+#include "base/trace_event/memory_dump_provider.h"
+
+namespace web_cache {
+
+class WebCacheMemoryDumpProvider
+    : public base::trace_event::MemoryDumpProvider {
+ public:
+  static WebCacheMemoryDumpProvider* GetInstance();
+
+  // base::trace_event::MemoryDumpProvider implementation.
+  bool OnMemoryDump(const base::trace_event::MemoryDumpArgs& args,
+                    base::trace_event::ProcessMemoryDump* pmd) override;
+
+ private:
+  friend struct base::DefaultLazyInstanceTraits<WebCacheMemoryDumpProvider>;
+
+  WebCacheMemoryDumpProvider();
+  ~WebCacheMemoryDumpProvider() override;
+
+  DISALLOW_COPY_AND_ASSIGN(WebCacheMemoryDumpProvider);
+};
+
+}  // namespace web_cache
+
+#endif  // COMPONENTS_WEB_CACHE_RENDERER_WEB_CACHE_MEMORY_DUMP_PROVIDER_H