Add coalesced KeyDown handling for arrow key scrolling.

third_party/WebKit/Source/web/WebViewImpl.cpp

Index: third_party/WebKit/Source/web/WebViewImpl.cpp
diff --git a/third_party/WebKit/Source/web/WebViewImpl.cpp b/third_party/WebKit/Source/web/WebViewImpl.cpp
index 79bae02503621254a2e5c402895f1427b4ceb906..6c8ca56276ceda87c689ca2010738389d97065f9 100644
--- a/third_party/WebKit/Source/web/WebViewImpl.cpp
+++ b/third_party/WebKit/Source/web/WebViewImpl.cpp
@@ -1677,6 +1677,7 @@ bool WebViewImpl::keyEventDefault(const WebKeyboardEvent& event) {
         return scrollViewWithKeyboard(keyCode, event.modifiers);
       }
       break;
+    case WebInputEvent::KeyDown:
     case WebInputEvent::RawKeyDown:
       if (event.modifiers == WebInputEvent::ControlKey) {
         switch (event.windowsKeyCode) {