Max start velocity should be greater than zero.

components/test_runner/event_sender.cc

Index: components/test_runner/event_sender.cc
diff --git a/components/test_runner/event_sender.cc b/components/test_runner/event_sender.cc
index 3a4b797d6e1975e1ecdd3bec535f02f6a7e302cb..abb7dd8f3dd7848be70d309876d73e398b47e49c 100644
--- a/components/test_runner/event_sender.cc
+++ b/components/test_runner/event_sender.cc
@@ -1923,6 +1923,14 @@ void EventSender::GestureFlingStart(float x,
     return;
   }
 
+  float max_start_velocity = std::max(fabs(velocity_x), fabs(velocity_y));
+  if (!max_start_velocity) {
+    v8::Isolate* isolate = blink::mainThreadIsolate();
+    isolate->ThrowException(v8::Exception::TypeError(
+      gin::StringToV8(isolate, "Invalid max start velocity.")));
+    return;
+  }
+
   event.x = x;
   event.y = y;
   event.globalX = event.x;