[tracing] Expose AddOwnershipEdge and CreateAllocatorDump with guid to blink. (blink-side).

public/platform/Platform.h

Index: public/platform/Platform.h
diff --git a/public/platform/Platform.h b/public/platform/Platform.h
index 7b8f0f648177cd1162c765da71fb29574fe85419..e0e1ec035197b77f07055480d73a9077e94f7805 100644
--- a/public/platform/Platform.h
+++ b/public/platform/Platform.h
@@ -572,6 +572,12 @@ public:
     // Returns a newly allocated WebProcessMemoryDump instance.
     virtual blink::WebProcessMemoryDump* createProcessMemoryDump() { return nullptr; }
 
+    typedef uint64_t WebMemoryAllocatorDumpGuid;
+
+    // Returns guid corresponding to the given string (the hash value) for
+    // creating a WebMemoryAllocatorDump.
+    virtual WebMemoryAllocatorDumpGuid createWebMemoryAllocatorDumpGuid(const WebString& guidStr) { return 0; }
+
     // GPU ----------------------------------------------------------------
     //
     // May return null if GPU is not supported.