[tracing] Add SkResourceCache as suballocation to avoid double counting.

content/child/child_discardable_shared_memory_manager.cc

Index: content/child/child_discardable_shared_memory_manager.cc
diff --git a/content/child/child_discardable_shared_memory_manager.cc b/content/child/child_discardable_shared_memory_manager.cc
index 5bdcef7337279443eb335df5bdde37cdbd926d88..180fb191e0a64a734fa0838c879f6f7dc3a82b70 100644
--- a/content/child/child_discardable_shared_memory_manager.cc
+++ b/content/child/child_discardable_shared_memory_manager.cc
@@ -192,6 +192,22 @@ ChildDiscardableSharedMemoryManager::AllocateLockedDiscardableMemory(
 
 bool ChildDiscardableSharedMemoryManager::OnMemoryDump(
     base::trace_event::ProcessMemoryDump* pmd) {
+  // Creates a common dump for all the sub-allocated objects from discardable
+  // memory. To expess any suballocation, the dump providers need to create a
+  // sub-allocation edge from this node.
+  // Eg. : pmd->AddSuballocation(skia_dump_guid,
+  //                             "discardable/allocated_objects");
+  base::trace_event::MemoryAllocatorDump* objects_dump =
+      pmd->CreateAllocatorDump("discardable/allocated_objects");

[petrcermak, 2015/07/29 11:53:34]

Any chance this name could be a constant like
https://code.google.com/p/chromium/codesearch#chromium/src/base/trace_event/m...
?

[ssid, 2015/07/29 16:20:51]

Done.

+  base::trace_event::MemoryAllocatorDump* discardable_segments_dump =
+      pmd->CreateAllocatorDump("discardable/segments");

[petrcermak, 2015/07/29 11:53:34]

Could this be a constant?

[ssid, 2015/07/29 16:20:51]

Done.

+
+  // The discardable memory segments will go under the dump
+  // "discardable/segments" and any sub-allocations under
+  // "discardable/allocated_objects" will be owned by it.

[petrcermak, 2015/07/29 11:53:34]

The relationship is reversed (in the comment).

[ssid, 2015/07/29 16:20:51]

Done.

+  pmd->AddOwnershipEdge(objects_dump->guid(),
+                        discardable_segments_dump->guid());
+
   base::AutoLock lock(lock_);
   return heap_.OnMemoryDump(pmd);
 }