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

base/memory/discardable_shared_memory.h

Index: base/memory/discardable_shared_memory.h
diff --git a/base/memory/discardable_shared_memory.h b/base/memory/discardable_shared_memory.h
index 74bbe8e95f427ba347d696e6c6e9c408e166e167..83c128af532def6d6ba9488dba6f440b5a2135f4 100644
--- a/base/memory/discardable_shared_memory.h
+++ b/base/memory/discardable_shared_memory.h
@@ -29,6 +29,13 @@ namespace base {
 // access to an instance of this class.
 class BASE_EXPORT DiscardableSharedMemory {
  public:
+  // Used by other allocators to expess sub-allocation from discardable memory
+  // heap for tracing. To expess any suballocation, the dump providers need to
+  // create a sub-allocation edge from this node.
+  // E.g.: ProcessMemoryDump::AddSuballocation(skia_dump_guid,
+  //                                           kAllocatedObjectsDumpName);
+  static const char kAllocatedObjectsDumpName[];
+
   enum LockResult { SUCCESS, PURGED, FAILED };
 
   DiscardableSharedMemory();