Use a new Supplement constructor for supplements in core/

third_party/WebKit/Source/core/loader/PrerendererClient.cpp

Index: third_party/WebKit/Source/core/loader/PrerendererClient.cpp
diff --git a/third_party/WebKit/Source/core/loader/PrerendererClient.cpp b/third_party/WebKit/Source/core/loader/PrerendererClient.cpp
index ded12a6c33700b25f5d64b8ad07d80b034389425..fba5ac2ad03913265852bc359f086890a27cf6e9 100644
--- a/third_party/WebKit/Source/core/loader/PrerendererClient.cpp
+++ b/third_party/WebKit/Source/core/loader/PrerendererClient.cpp
@@ -44,9 +44,12 @@ const char* PrerendererClient::supplementName() {
 PrerendererClient* PrerendererClient::from(Page* page) {
   PrerendererClient* supplement = static_cast<PrerendererClient*>(
       Supplement<Page>::from(page, supplementName()));
+  DCHECK(supplement);
   return supplement;
 }
 
+PrerendererClient::PrerendererClient(Page& page) : Supplement<Page>(page) {}
+
 void providePrerendererClientTo(Page& page, PrerendererClient* client) {
   PrerendererClient::provideTo(page, PrerendererClient::supplementName(),
                                client);