Switch tracing to new flexbox.

tracing/tracing/ui/extras/drive/index.html

Index: tracing/tracing/ui/extras/drive/index.html
diff --git a/tracing/tracing/ui/extras/drive/index.html b/tracing/tracing/ui/extras/drive/index.html
index 8d815671ca03a906132e5851660bbe380bdf7cf7..7cb67311ac8508deb2886ef9ccbb6e359bc25c3e 100644
--- a/tracing/tracing/ui/extras/drive/index.html
+++ b/tracing/tracing/ui/extras/drive/index.html
@@ -20,11 +20,11 @@ found in the LICENSE file.
       padding: 0;
       width: 100%;
       height: 100%;
-      display: -webkit-flex;
-      -webkit-flex-direction: column;
+      display: flex;
+      flex-direction: column;
     }
     body > x-timeline-view {
-      -webkit-flex: 1 1 auto;
+      flex: 1 1 auto;
       overflow: hidden;
       position: absolute;
       top: 0px;