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

public/platform/WebProcessMemoryDump.h

Index: public/platform/WebProcessMemoryDump.h
diff --git a/public/platform/WebProcessMemoryDump.h b/public/platform/WebProcessMemoryDump.h
index cdaf14358e54a1a9fcee99d45140f32212bd3071..4deedacfbd8df795107b40485554690a258e0aa6 100644
--- a/public/platform/WebProcessMemoryDump.h
+++ b/public/platform/WebProcessMemoryDump.h
@@ -7,11 +7,10 @@
 
 #include "WebCommon.h"
 #include "WebString.h"
+#include "public/platform/WebMemoryAllocatorDump.h"
 
 namespace blink {
 
-class WebMemoryAllocatorDump;
-
 // A container which holds all the dumps for the various allocators for a given
 // process. Embedders of WebMemoryDumpProvider are expected to populate a
 // WebProcessMemoryDump instance with the stats of their allocators.
@@ -24,6 +23,14 @@ public:
     // dump within the scope of a ProcessMemoryDump. It is possible to express
     // nesting by means of a slash-separated path naming (e.g.,
     // "allocator_name/arena_1/subheap_X").
+    // |guid| is  an optional identifier, unique among all processes within the
+    // scope of a global dump. This is only relevant when using
+    // AddOwnershipEdge(). If omitted, it will be automatically generated.
+    virtual WebMemoryAllocatorDump* createMemoryAllocatorDump(const WebString& absoluteName, const WebMemoryAllocatorDumpGuid& guid)
+    {
+        return nullptr;

[Primiano Tucci (use gerrit), 2015/06/08 09:39:16]

Can you plz add BLINK_ASSERT_NOT_REACHED(); here and below for uniformity.

[ssid, 2015/06/08 14:29:19]

Done.

+    }
+
     virtual WebMemoryAllocatorDump* createMemoryAllocatorDump(const WebString& absoluteName)
     {
         return nullptr;
@@ -51,6 +58,22 @@ public:
     {
         BLINK_ASSERT_NOT_REACHED();
     }
+
+    // Adds an ownership relationship between two MemoryAllocatorDump(s) with
+    // the semantics: |source| owns |target|, and has the effect of attributing
+    // the memory usage of |target| to |source|. |importance| is optional and
+    // relevant only for the cases of co-ownership, where it acts as a z-index:
+    // the owner with the highest importance will be attributed |target|'s
+    // memory.
+    virtual void AddOwnershipEdge(const WebMemoryAllocatorDumpGuid& source, const WebMemoryAllocatorDumpGuid& target, int importance)
+    {
+        BLINK_ASSERT_NOT_REACHED();
+    }
+
+    virtual void AddOwnershipEdge(const WebMemoryAllocatorDumpGuid& source, const WebMemoryAllocatorDumpGuid& target)
+    {
+        BLINK_ASSERT_NOT_REACHED();
+    }
 };
 
 } // namespace blink