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

base/memory/discardable_memory_allocator.cc

Index: base/memory/discardable_memory_allocator.cc
diff --git a/base/memory/discardable_memory_allocator.cc b/base/memory/discardable_memory_allocator.cc
index 002a3ba5e4763c360dc0a96861d0c53758bdb3bc..0b163d68cb94729a62592da19fc5aacb2a88e33e 100644
--- a/base/memory/discardable_memory_allocator.cc
+++ b/base/memory/discardable_memory_allocator.cc
@@ -5,6 +5,8 @@
 #include "base/memory/discardable_memory_allocator.h"
 
 #include "base/logging.h"
+#include "base/trace_event/memory_allocator_dump.h"
+#include "base/trace_event/process_memory_dump.h"
 
 namespace base {
 namespace {
@@ -31,4 +33,9 @@ DiscardableMemoryAllocator* DiscardableMemoryAllocator::GetInstance() {
   return g_allocator;
 }
 
+// static
+const char* DiscardableMemoryAllocator::GetMemoryPoolNameForTracing() {
+  return "discardable/allocated_objects";
+}
+
 }  // namespace base