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

base/memory/discardable_shared_memory.cc

Index: base/memory/discardable_shared_memory.cc
diff --git a/base/memory/discardable_shared_memory.cc b/base/memory/discardable_shared_memory.cc
index 0f85c1fe903d612ecf055043c1a0d84d362ddbf7..bd11c8ac553e32482bc0a77b2aab0bcd40364c3b 100644
--- a/base/memory/discardable_shared_memory.cc
+++ b/base/memory/discardable_shared_memory.cc
@@ -97,6 +97,10 @@ size_t AlignToPageSize(size_t size) {
 
 }  // namespace
 
+// static
+const char DiscardableSharedMemory::kAllocatedObjectsDumpName[] =
+    "discardable/allocated_objects";
+
 DiscardableSharedMemory::DiscardableSharedMemory()
     : mapped_size_(0), locked_page_count_(0) {
 }