Break dependency on ChromeClientImpl for WebPluginContainerImpl.

third_party/WebKit/Source/core/loader/EmptyClients.h

Index: third_party/WebKit/Source/core/loader/EmptyClients.h
diff --git a/third_party/WebKit/Source/core/loader/EmptyClients.h b/third_party/WebKit/Source/core/loader/EmptyClients.h
index c367de21786c764d451ad5123b9f11da62d3e212..40299042b1d2245667e46b2156b492db42d4cfc5 100644
--- a/third_party/WebKit/Source/core/loader/EmptyClients.h
+++ b/third_party/WebKit/Source/core/loader/EmptyClients.h
@@ -238,6 +238,8 @@ class CORE_EXPORT EmptyChromeClient : public ChromeClient {
   void UnregisterPopupOpeningObserver(PopupOpeningObserver*) override {}
   void NotifyPopupOpeningObservers() const {}
 
+  void SetCursorForPlugin(const WebCursorInfo&, LocalFrame*) override {}
+
   std::unique_ptr<WebFrameScheduler> CreateFrameScheduler(
       BlameContext*) override;
 };