Add deprecation message for -webkit-background-composite

third_party/WebKit/Source/core/frame/FrameHost.h

Index: third_party/WebKit/Source/core/frame/FrameHost.h
diff --git a/third_party/WebKit/Source/core/frame/FrameHost.h b/third_party/WebKit/Source/core/frame/FrameHost.h
index a937282d171c4ecf2d03f40d7d6d0f4652d029f2..554fe348669cfba9efa606b915e10f86bbb7a84e 100644
--- a/third_party/WebKit/Source/core/frame/FrameHost.h
+++ b/third_party/WebKit/Source/core/frame/FrameHost.h
@@ -45,6 +45,7 @@ namespace blink {
 
 class ChromeClient;
 class ConsoleMessageStorage;
+class DeprecationHelper;
 class EventHandlerRegistry;
 class Page;
 class PageScaleConstraintsSet;
@@ -72,6 +73,7 @@ public:
     Settings& settings() const;
     ChromeClient& chromeClient() const;
     UseCounter& useCounter() const;
+    DeprecationHelper& deprecationHelper() const;
 
     // Corresponds to pixel density of the device where this Page is
     // being displayed. In multi-monitor setups this can vary between pages.