[Media Controls] Fix integer cast

MediaControlSliderElement is causing a ClusterFuzz error
because we are casting a float to an int that could
overflow.

BUG=852364

Change-Id: Ic454a79ebf6ef8d40f85e054a70cb87030c6db9c
Reviewed-on: https://chromium-review.googlesource.com/1131921
Commit-Queue: Becca Hughes <beccahughes@chromium.org>
Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Cr-Commit-Position: refs/heads/master@{#574191}

third_party/blink/renderer/modules/media_controls/elements/media_control_slider_element.cc

@@ -21,8 +21,9 @@ void SetSegmentDivPosition(blink::HTMLDivElement* segment,
                            blink::MediaControlSliderElement::Position position,
                            int width,
                            float zoom_factor) {
-  int segment_width = int((position.width * width) / zoom_factor);
-  int segment_left = int((position.left * width) / zoom_factor);
+  int segment_width =
+      clampTo<int>(floor((position.width * width) / zoom_factor));
+  int segment_left = clampTo<int>(floor((position.left * width) / zoom_factor));
   int current_width = 0;
   int current_left = 0;