Make the width of overlay pages flexible.

chrome/browser/resources/options/options_page.css

Index: chrome/browser/resources/options/options_page.css
diff --git a/chrome/browser/resources/options/options_page.css b/chrome/browser/resources/options/options_page.css
index 16ccd42d0f56b6a6942249d7f605e19266215cf5..875bae2c0246ab8d2ae080f3e359f51292df95a3 100644
--- a/chrome/browser/resources/options/options_page.css
+++ b/chrome/browser/resources/options/options_page.css
@@ -25,6 +25,9 @@
   bottom: 0;
   z-index: 10;
   padding: 20px;
+  display: -webkit-box;
+  -webkit-box-align: start;
+  -webkit-box-pack: center;
 }
 
 #close-overlay {
@@ -44,11 +47,11 @@ html[dir='rtl'] #close-overlay {
   left: -20px;
 }
 
-#overlayview .button-strip {
+.overlay .button-strip {
   text-align: end;
 }
 
-#overlayview {
+.overlay > div {
   background: white;
   border-radius: 5px;
   padding: 30px;