[Media Router WebUI] Fix search input highlight.

chrome/browser/resources/media_router/elements/media_router_container/media_router_container.css

Index: chrome/browser/resources/media_router/elements/media_router_container/media_router_container.css
diff --git a/chrome/browser/resources/media_router/elements/media_router_container/media_router_container.css b/chrome/browser/resources/media_router/elements/media_router_container/media_router_container.css
index d876977e55072913cf7a78d30cfaf01c47eba06a..5e0f42e68c434ae415f203ffc0cc511fe0e890ad 100644
--- a/chrome/browser/resources/media_router/elements/media_router_container/media_router_container.css
+++ b/chrome/browser/resources/media_router/elements/media_router_container/media_router_container.css
@@ -198,6 +198,10 @@ paper-menu {
 }
 
 #sink-search-input {
+  --paper-input-container: {
+    margin: 8px 0;
+    padding: 0;
+  };
   --paper-input-container-focus-color: rgb(33, 150, 243);
   --paper-input-container-input: {
     font-size: 12px;