Add UMA to estimate deroppable memory usage of encoded data size in Resources

third_party/WebKit/Source/core/fetch/ResourceClient.h

Index: third_party/WebKit/Source/core/fetch/ResourceClient.h
diff --git a/third_party/WebKit/Source/core/fetch/ResourceClient.h b/third_party/WebKit/Source/core/fetch/ResourceClient.h
index d7c071055670e45ef8f38a0db4e54b57274693e2..4bfbfc92441898eaa29c0b511e5716430bed83b2 100644
--- a/third_party/WebKit/Source/core/fetch/ResourceClient.h
+++ b/third_party/WebKit/Source/core/fetch/ResourceClient.h
@@ -53,6 +53,8 @@ class CORE_EXPORT ResourceClient : public GarbageCollectedMixin {
     return BaseResourceType;
   }
 
+  virtual bool isReloadable() const { return true; }
+
   // Name for debugging, e.g. shown in memory-infra.
   virtual String debugName() const = 0;