[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, 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;
     }
 
     // Gets a previously created MemoryAllocatorDump given its name.
     virtual WebMemoryAllocatorDump* getMemoryAllocatorDump(const WebString& absoluteName) const
     {
         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()
     {
         BLINK_ASSERT_NOT_REACHED();
     }
 
     // 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)
     {
         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
 
 #endif // WebProcessMemoryDump_h