Prepare SyntheticPointerAction to handle touch actions for multiple fingers

content/browser/renderer_host/input/synthetic_touch_pointer.cc

Index: content/browser/renderer_host/input/synthetic_touch_pointer.cc
diff --git a/content/browser/renderer_host/input/synthetic_touch_pointer.cc b/content/browser/renderer_host/input/synthetic_touch_pointer.cc
index ca4637a6711795e825a10c7069bed92afbd6e457..2b1fa64893ab44881444996940028454257ba0ca 100644
--- a/content/browser/renderer_host/input/synthetic_touch_pointer.cc
+++ b/content/browser/renderer_host/input/synthetic_touch_pointer.cc
@@ -43,4 +43,9 @@ void SyntheticTouchPointer::Release(int index,
   touch_event_.ReleasePoint(index);
 }
 
+SyntheticGestureParams::GestureSourceType SyntheticTouchPointer::SourceType()
+    const {
+  return SyntheticGestureParams::TOUCH_INPUT;
+}
+
 }  // namespace content