Use CSS3 flex to lay out Files.app components.

ui/file_manager/file_manager/foreground/css/table.css

Index: ui/file_manager/file_manager/foreground/css/table.css
diff --git a/ui/file_manager/file_manager/foreground/css/table.css b/ui/file_manager/file_manager/foreground/css/table.css
index 83516993103414213f0e7c2d43815cdffe4d7710..2a16527f6e049d470028a901d9835a26ccb0b980 100644
--- a/ui/file_manager/file_manager/foreground/css/table.css
+++ b/ui/file_manager/file_manager/foreground/css/table.css
@@ -13,13 +13,13 @@ html.col-resize * {
 }
 
 .table-row {
-  display: -webkit-box;
+  display: flex;
   text-align: start;
   width: 100%;
 }
 
 .table-row-cell {
-  display: -webkit-box;
+  display: flex;
   overflow: hidden;
 }
 
@@ -37,7 +37,7 @@ html.col-resize * {
 .table-header-inner {
   -webkit-user-select: none;
   cursor: default;
-  display: -webkit-box;
+  display: flex;
   position: relative;
   text-align: start;
 }