Notify OverscrollController of gesture events in plugins.

content/browser/renderer_host/overscroll_controller.cc

Index: content/browser/renderer_host/overscroll_controller.cc
diff --git a/content/browser/renderer_host/overscroll_controller.cc b/content/browser/renderer_host/overscroll_controller.cc
index ef9fcafce86f38870e825feb8b61a89d939074e0..7f32ae0fcf1125a0eff83282e1a2a443dd73578c 100644
--- a/content/browser/renderer_host/overscroll_controller.cc
+++ b/content/browser/renderer_host/overscroll_controller.cc
@@ -51,6 +51,16 @@ bool OverscrollController::ShouldProcessEvent(
     case blink::WebInputEvent::kGestureScrollEnd: {
       const blink::WebGestureEvent& gesture =
           static_cast<const blink::WebGestureEvent&>(event);
+
+      // GestureScrollBegin and GestureScrollEnd events are created to wrap
+      // individual resent GestureScrollUpdates from a plugin. Hence these
+      // should not be used to indicate the beginning/end of the overscroll.
+      // TODO(mcnee): When we remove BrowserPlugin, delete this code.
+      // See crbug.com/533069
+      if (gesture.resending_plugin_id != -1 &&
+          event.GetType() != blink::WebInputEvent::kGestureScrollUpdate)
+        return false;
+
       blink::WebGestureEvent::ScrollUnits scrollUnits;
       switch (event.GetType()) {
         case blink::WebInputEvent::kGestureScrollBegin: