[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 91136f19852769e96912b0a042f64cb9a48a40ed..3515d1821c76263c68b77e33801b763c42c7ee36 100644
--- a/public/platform/WebMemoryAllocatorDump.h
+++ b/public/platform/WebMemoryAllocatorDump.h
@@ -9,6 +9,7 @@
 #include "WebString.h"
 
 namespace blink {
+typedef uint64_t WebMemoryAllocatorDumpGuid;

[Rick Byers, 2015/06/11 14:12:16]

this is redundant with the definition in the other file, right?

[ssid, 2015/06/11 14:14:44]

I added this here to avoid an extra #include. I did the same in Platform.h too.
Do you think i should include the file here?

[ssid, 2015/06/11 14:49:06]

Sorry, I misunderstood the comment.

So, this is the file where this typedef should be present. But the Platform.h
has an extra typedef to avoid an include. This is a pattern in the other
typedefs there, eg. TraceEventAPIAtomicWord and TraceEventHandle. That is why I
added a redundant typedef there.

 
 // A container which holds all the attributes of a particular dump for a given
 // allocator.
@@ -27,6 +28,18 @@ public:
     virtual void AddScalar(const WebString& name, const char* units, uint64_t value) { BLINK_ASSERT_NOT_REACHED(); }
     virtual void AddScalarF(const WebString& name, const char* units, double value) { BLINK_ASSERT_NOT_REACHED(); }
     virtual void AddString(const WebString& name, const char* units, const WebString& value) { BLINK_ASSERT_NOT_REACHED(); }
+
+    // |guid| is an optional global dump identifier, unique across all processes
+    // within the scope of a global dump. It is only required when using the
+    // graph APIs (see AddOwnershipEdge) to express retention / suballocation or
+    // cross process sharing. See crbug.com/492102 for design docs.
+    // Subsequent MemoryAllocatorDump(s) with the same |absolute_name| are
+    // expected to have the same guid.
+    virtual WebMemoryAllocatorDumpGuid guid() const
+    {
+        BLINK_ASSERT_NOT_REACHED();
+        return 0;
+    }
 };
 
 } // namespace blink