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

public/platform/WebProcessMemoryDump.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef WebProcessMemoryDump_h
 #define WebProcessMemoryDump_h
 
 #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.
 class BLINK_PLATFORM_EXPORT WebProcessMemoryDump {
 public:
     virtual ~WebProcessMemoryDump();
 
     // Creates a new MemoryAllocatorDump with the given name and returns the
     // empty object back to the caller. |absoluteName| uniquely identifies the
     // 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)

[Primiano Tucci (use gerrit), 2015/06/02 12:38:52]

Well at this point you should swap the order of the two and have the overload
with the GUID here, and the reduced one below

[ssid, 2015/06/02 16:08:02]

Done.

     {
         return nullptr;
     }
 
+    virtual WebMemoryAllocatorDump* createMemoryAllocatorDump(const WebString& absoluteName, const WebMemoryAllocatorDumpGuid& guid)
+    {
+        return nullptr;
+    }
+
     // Removes all the WebMemoryAllocatorDump(s) contained in this instance.
     // This WebProcessMemoryDump can be safely reused as if it was new once this
     // method returns.
     virtual void clear()
     {
     }
 
     // Merges all WebMemoryAllocatorDump(s) contained in |other| inside this
     // WebProcessMemoryDump, transferring their ownership to this instance.
     // |other| will be an empty WebProcessMemoryDump after this method returns
     // and can be reused as if it was new.
     virtual void takeAllDumpsFrom(WebProcessMemoryDump* other)
     {
     }
+
+    // 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)

[Primiano Tucci (use gerrit), 2015/06/02 12:38:52]

nit, missing  & (const WMADG& source).
Same below

[ssid, 2015/06/02 16:08:02]

Done.

+    {
+    }
+
+    virtual void AddOwnershipEdge(const WebMemoryAllocatorDumpGuid source, const WebMemoryAllocatorDumpGuid target)
+    {
+    }
 };
 
 } // namespace blink
 
 #endif // WebProcessMemoryDump_h