cc: Remove memory state from tile management

cc/resources/resource_pool.h

Index: cc/resources/resource_pool.h
diff --git a/cc/resources/resource_pool.h b/cc/resources/resource_pool.h
index 651f1d4ee9f06b5cd32586987bbf6452bbbfd340..0f3b2b8137733dab0eabb0363a909ca1be788902 100644
--- a/cc/resources/resource_pool.h
+++ b/cc/resources/resource_pool.h
@@ -46,6 +46,10 @@ class CC_EXPORT ResourcePool {
       size_t max_memory_usage_bytes,
       size_t max_unused_memory_usage_bytes);
 
+  size_t acquired_memory_usage_bytes() const {
+    return memory_usage_bytes_ - unused_memory_usage_bytes_;
+  }
+
  protected:
   explicit ResourcePool(ResourceProvider* resource_provider);