[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..fe1c09bfffee2438e5905fe377fd2d86ae952ae5 100644
--- a/public/platform/WebMemoryAllocatorDump.h
+++ b/public/platform/WebMemoryAllocatorDump.h
@@ -10,10 +10,45 @@
 
 namespace blink {
 
+// Class which holds the guid of the WebMemoryAllocatorDump.
+class BLINK_PLATFORM_EXPORT WebMemoryAllocatorDumpGuid {
+public:
+    explicit WebMemoryAllocatorDumpGuid(const uint64_t guid)
+        : m_guidInt(guid)
+    {
+    }
+
+    explicit WebMemoryAllocatorDumpGuid(const WebString& guid)
+        : m_guidInt(HashGuidString(guid))
+    {
+    }
+
+private:

[Primiano Tucci (use gerrit), 2015/06/09 20:51:34]

I think this should be protected for sake of clarity.

+    virtual uint64_t HashGuidString(const WebString& guid) const
+    {
+        BLINK_ASSERT_NOT_REACHED();
+        return 0;
+    }
+
+    uint64_t m_guidInt;
+};
+
 // A container which holds all the attributes of a particular dump for a given
 // allocator.
 class BLINK_PLATFORM_EXPORT WebMemoryAllocatorDump {
 public:
+    // TODO(ssid): This constructor should be removed once the usage is
+    // changed in chromium side (ETA: 15/06/2015).
+    WebMemoryAllocatorDump()
+        : m_guid(WebMemoryAllocatorDumpGuid(0))
+    {
+    }
+
+    WebMemoryAllocatorDump(WebMemoryAllocatorDumpGuid guid)
+        : m_guid(guid)
+    {
+    }
+
     virtual ~WebMemoryAllocatorDump();
 
     // Adds a scalar attribute to the dump.
@@ -27,6 +62,20 @@ 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.
+    const WebMemoryAllocatorDumpGuid& guid() const
+    {
+        return m_guid;
+    }
+
+private:
+    WebMemoryAllocatorDumpGuid m_guid;
 };
 
 } // namespace blink