[polymer] Add back missing code in input_latency_side_panel.html

tracing/tracing/ui/extras/side_panel/input_latency_side_panel.html

Index: tracing/tracing/ui/extras/side_panel/input_latency_side_panel.html
diff --git a/tracing/tracing/ui/extras/side_panel/input_latency_side_panel.html b/tracing/tracing/ui/extras/side_panel/input_latency_side_panel.html
index abeaded0c9759886c137ae551370552b7a3713bb..085050db936c08ae3ea2f64a40b68424a7c3ba6c 100644
--- a/tracing/tracing/ui/extras/side_panel/input_latency_side_panel.html
+++ b/tracing/tracing/ui/extras/side_panel/input_latency_side_panel.html
@@ -116,6 +116,9 @@ Polymer({
       this.latencyChart_.brushedRange = r;
       return;
     }
+    r = this.latencyChart_.computeBrushRangeFromIndices(
+        this.mouseDownIndex_, this.curMouseIndex_);
+    this.latencyChart_.brushedRange = r;
 
     // Based on the brushed range, update the selection of LatencyInfo in
     // the timeline view by sending a selectionChange event.