Adding blink gc memory dump infrastructure for thread specific dumps.

Source/platform/heap/BlinkGCMemoryDumpProvider.h

Index: Source/platform/heap/BlinkGCMemoryDumpProvider.h
diff --git a/Source/platform/heap/BlinkGCMemoryDumpProvider.h b/Source/platform/heap/BlinkGCMemoryDumpProvider.h
index 1ed934947dbb4b651a9b3213e8327a56b3d6108c..a5e8c156edd18d165121867a4d3ce84519ce0d7a 100644
--- a/Source/platform/heap/BlinkGCMemoryDumpProvider.h
+++ b/Source/platform/heap/BlinkGCMemoryDumpProvider.h
@@ -6,9 +6,13 @@
 #define BlinkGCMemoryDumpProvider_h
 
 #include "platform/PlatformExport.h"
+#include "platform/TraceEvent.h"
 #include "public/platform/WebMemoryDumpProvider.h"
+#include "wtf/OwnPtr.h"
+#include "wtf/text/WTFString.h"
 
 namespace blink {
+class WebMemoryAllocatorDump;
 
 class PLATFORM_EXPORT BlinkGCMemoryDumpProvider final : public WebMemoryDumpProvider {
 public:
@@ -18,8 +22,22 @@ public:
     // WebMemoryDumpProvider implementation.
     bool onMemoryDump(WebProcessMemoryDump*) override;
 
+    static inline bool isMemoryTracingEnabled()
+    {
+        // TODO(ssid): Change this to use api from memory-infra to check tracing
+        // memory_tracing_enabled (crbug.com/490087).
+        bool enabled;
+        TRACE_EVENT_CATEGORY_GROUP_ENABLED(TRACE_DISABLED_BY_DEFAULT("memory-infra"), &enabled);
+        return enabled;
+    }
+
+    WebMemoryAllocatorDump* createMemoryAllocatorDumpForLastGC(const String& absoluteName);
+    void clearLastGCProcessMemoryDump();
+
 private:
     BlinkGCMemoryDumpProvider();
+
+    OwnPtr<WebProcessMemoryDump> m_lastProcessMemoryDump;
 };
 
 } // namespace blink