Add window buttons (close and maximize) to the Files.app's new UI.

chrome/browser/resources/file_manager/css/common.css

Index: chrome/browser/resources/file_manager/css/common.css
diff --git a/chrome/browser/resources/file_manager/css/common.css b/chrome/browser/resources/file_manager/css/common.css
index 73bf0d34eccaf748a9ec24ea4bc0b665b2281d3f..7f1964f049a1d424748242201993c562b51dd90f 100644
--- a/chrome/browser/resources/file_manager/css/common.css
+++ b/chrome/browser/resources/file_manager/css/common.css
@@ -414,6 +414,8 @@ body[new-ui] select {
   -webkit-box-shadow: inset 0 1px 1px 0 rgb(255, 255, 255);
   background-color: rgb(250, 250, 250);
   background-image: none;
+  background-position: center;
+  background-repeat: no-repeat;
   border: 1px solid rgb(255, 255, 255);
   border-bottom: 1px solid rgb(180, 180, 180);
   border-left: 1px solid rgb(220, 220, 220);
@@ -447,7 +449,8 @@ body[new-ui] input[type='button']:hover,
 body[new-ui] input[type='submit']:hover,
 body[new-ui] select:hover {
   -webkit-box-shadow: 0 1px 2px rgba(0, 0, 0, 0.1);
-  background: #ebebeb -webkit-linear-gradient(#fefefe, #f8f8f8 40%, #f0f0f0);
+  background-color: #ebebeb;
+  background-image: -webkit-linear-gradient(#fefefe, #f8f8f8 40%, #f0f0f0);
   border-color: rgb(190, 190, 190);
   color: #222;
 }
@@ -456,7 +459,8 @@ body:not([new-ui]) button:active,
 body:not([new-ui]) input[type='button']:active,
 body:not([new-ui]) input[type='submit']:active {
   -webkit-box-shadow: inset 0 1px 2px rgba(0, 0, 0, 0.1);
-  background: #ebebeb -webkit-linear-gradient(#f4f4f4, #efefef 40%, #dcdcdc);
+  background-color: #ebebeb;
+  background-image: -webkit-linear-gradient(#f4f4f4, #efefef 40%, #dcdcdc);
   color: #333;
 }
 
@@ -464,7 +468,8 @@ body[new-ui] button:active,
 body[new-ui] input[type='button']:active,
 body[new-ui] input[type='submit']:active {
   -webkit-box-shadow: inset 0 1px 2px rgba(0, 0, 0, 0.1);
-  background: #ebebeb -webkit-linear-gradient(#f4f4f4, #efefef 40%, #dcdcdc);
+  background-color: #ebebeb;
+  background-image: -webkit-linear-gradient(#f4f4f4, #efefef 40%, #dcdcdc);
   color: #333;
 }