Explicitly reset preferred lang and text track state in media/track

Add cleanup handlers that resets "user preferred languages" and "text
track kind user preference", or just reset them outright, to see if this
has any bearing on the problem (works locally.)

Bug: 664844
Change-Id: I6237ace717fbaf6f5203d8a051950763547e191f
Reviewed-on: https://chromium-review.googlesource.com/757102Reviewed-by: srirama chandra sekhar <srirama.m@samsung.com>
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Cr-Commit-Position: refs/heads/master@{#515919}

third_party/WebKit/LayoutTests/media/track/track-kind-user-preference.html

@@ -16,6 +16,10 @@
 <script>
 async_test(function(t) {
     var video = document.querySelector("video");
+    t.add_cleanup(function() {
+        internals.setUserPreferredLanguages([]);
+        internals.settings.setTextTrackKindUserPreference("default");
+    });
     internals.setUserPreferredLanguages(["jp", "es", "en", "fr"]);
     video.src = findMediaFile("video", "../content/test");
 

third_party/WebKit/LayoutTests/media/track/track-language-preference-no-crash.html

@@ -9,5 +9,8 @@ test(function() {
     // Set user preferred languages.
     internals.setUserPreferredLanguages(['jp', 'es-ES', 'en', 'fr']);
     internals.settings.setTextTrackKindUserPreference('captions');
+
+    internals.setUserPreferredLanguages([]);
+    internals.settings.setTextTrackKindUserPreference("default");
 });
-</script>
\ No newline at end of file
+</script>

third_party/WebKit/LayoutTests/media/track/track-language-preference.html

@@ -7,6 +7,10 @@
 <script>
 async_test(function(t) {
     var video = document.querySelector("video");
+    t.add_cleanup(function() {
+        internals.setUserPreferredLanguages([]);
+        internals.settings.setTextTrackKindUserPreference("default");
+    });
 
     // Set user preferred languages.
     internals.setUserPreferredLanguages(['jp', 'es-ES', 'en', 'fr']);
@@ -84,4 +88,4 @@ async_test(function(t) {
         timer = setTimeout(runNextTest, 200);
     }
 });
-</script>
\ No newline at end of file
+</script>