Fix WebKeyboardEvent interruption of compositor scrolling

content/renderer/input/input_handler_proxy.cc

Index: content/renderer/input/input_handler_proxy.cc
diff --git a/content/renderer/input/input_handler_proxy.cc b/content/renderer/input/input_handler_proxy.cc
index 2793576bd3989fda204ba550ad3a516539bd8691..6172e601cfc4797ec568561b160756c8bcbdfd41 100644
--- a/content/renderer/input/input_handler_proxy.cc
+++ b/content/renderer/input/input_handler_proxy.cc
@@ -250,7 +250,10 @@ InputHandlerProxy::EventDisposition InputHandlerProxy::HandleInputEvent(
     }
     return DROP_EVENT;
   } else if (WebInputEvent::isKeyboardEventType(event.type)) {
-    CancelCurrentFling(true);
+    // Only call |CancelCurrentFling()| if a fling was active, as it will
+    // otherwise disrupt an in-progress touch scroll.
+    if (fling_curve_)
+      CancelCurrentFling(true);
   } else if (event.type == WebInputEvent::MouseMove) {
     const WebMouseEvent& mouse_event =
         *static_cast<const WebMouseEvent*>(&event);