Files app: Expand region of audio control in quick view.

The default audio controls for <audio> tag gets bigger recently.
To fit the control, the region for audio control in quick view needs to be
bigger.
This is a quick fix to fix the regression.
The quick view should handle any size of audio control. It should be fixed by a
separated CL.

Bug: 826860
Test: Manually tested by mp3 files with and without cover arts.
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: Ib6cae6bc514d05090b65e076fcc276c8a3aabbca
Reviewed-on: https://chromium-review.googlesource.com/984914Reviewed-by: Tatsuhisa Yamaguchi <yamaguchi@chromium.org>
Commit-Queue: Naoki Fukino <fukino@chromium.org>
Cr-Commit-Position: refs/heads/master@{#548014}

ui/file_manager/file_manager/foreground/elements/files_safe_media.html

@@ -11,7 +11,7 @@
         width: 100%;
       }
       #content.audio {
-        height: 32px;
+        height: 54px;
       }
       webview {
         display: inline-block;