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

public/platform/WebMemoryAllocatorDump.h

Index: public/platform/WebMemoryAllocatorDump.h
diff --git a/public/platform/WebMemoryAllocatorDump.h b/public/platform/WebMemoryAllocatorDump.h
index 5b3035922c394d3260ad7702a1469411450a6d19..6d2d5c2416a1e4eac55fd45ef6964f14d4bdf8db 100644
--- a/public/platform/WebMemoryAllocatorDump.h
+++ b/public/platform/WebMemoryAllocatorDump.h
@@ -10,6 +10,33 @@
 
 namespace blink {
 
+// Class which has the guid of the WebMemoryAllocatorDump. The guid can either
+// be uint64_t or WebString.
+struct BLINK_PLATFORM_EXPORT WebMemoryAllocatorDumpGuid {
+    enum GuidType {
+        Int64Type,

[Primiano Tucci (use gerrit), 2015/05/29 11:24:53]

Technically this is a uint64 not int64, so either you call this Uint64Type or
just IntType (I'd prefer the latter)

[ssid, 2015/05/29 15:50:48]

Done.

+        StringType
+    };
+
+    const uint64_t guidInt64;
+    const WebString guidString;
+    const GuidType type;
+
+    explicit WebMemoryAllocatorDumpGuid(const uint64_t guid)
+        : guidInt64(guid)
+        , guidString()
+        , type(Int64Type)
+    {
+    }
+
+    explicit WebMemoryAllocatorDumpGuid(const WebString& guid)
+        : guidInt64(0)
+        , guidString(guid)
+        , type(StringType)
+    {
+    }
+};
+
 // A container which holds all the attributes of a particular dump for a given
 // allocator.
 class BLINK_PLATFORM_EXPORT WebMemoryAllocatorDump {