Added basic client hints support.

Source/core/frame/LocalFrame.h

Index: Source/core/frame/LocalFrame.h
diff --git a/Source/core/frame/LocalFrame.h b/Source/core/frame/LocalFrame.h
index c9e2193a7600891d7f30a5f22753319478e0a6e1..54df8d9493c8f8408a35b8e52707f3cd53e2e275 100644
--- a/Source/core/frame/LocalFrame.h
+++ b/Source/core/frame/LocalFrame.h
@@ -175,6 +175,11 @@ namespace blink {
 #endif
         DisplayItemClient displayItemClient() const { return toDisplayItemClient(this); }
 
+        void setShouldSendDPRHint() { m_shouldSendDPRHint = true; }
+        void setShouldSendRWHint() { m_shouldSendRWHint = true; }
+        bool shouldSendDPRHint() { return m_shouldSendDPRHint; }
+        bool shouldSendRWHint() { return m_shouldSendRWHint; }
+
     // ========
 
     private:
@@ -228,6 +233,9 @@ namespace blink {
         bool m_inViewSourceMode;
 
         RefPtrWillBeMember<InstrumentingAgents> m_instrumentingAgents;
+
+        bool m_shouldSendDPRHint;
+        bool m_shouldSendRWHint;
     };
 
     inline void LocalFrame::init()