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..e20f28ea724725d2ecd174ff702f8715c9889a8f 100644
--- a/Source/platform/heap/BlinkGCMemoryDumpProvider.h
+++ b/Source/platform/heap/BlinkGCMemoryDumpProvider.h
@@ -7,8 +7,11 @@
 
 #include "platform/PlatformExport.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 +21,19 @@ public:
     // WebMemoryDumpProvider implementation.
     bool onMemoryDump(WebProcessMemoryDump*) override;
 
+    // The returned WebMemoryAllocatorDump is owned by
+    // BlinkGCMemoryDumpProvider, and should not be retained (just used to
+    // dump in the current call stack).
+    WebMemoryAllocatorDump* createMemoryAllocatorDumpForCurrentGC(const String& absoluteName);
+
+    // This must be called before taking a new process-wide GC snapshot, to
+    // clear the previous dumps.
+    void clearProcessDumpForCurrentGC();
+
 private:
     BlinkGCMemoryDumpProvider();
+
+    OwnPtr<WebProcessMemoryDump> m_currentProcessMemoryDump;
 };
 
 } // namespace blink