MD Downloads: reduce the size of the ellided, displayed download URL

chrome/test/data/webui/md_downloads/layout_tests.js

Index: chrome/test/data/webui/md_downloads/layout_tests.js
diff --git a/chrome/test/data/webui/md_downloads/layout_tests.js b/chrome/test/data/webui/md_downloads/layout_tests.js
index 820a7f4e616aee74ec5241315b18beb1dd8328b0..e55af715c01a0e2c73fb48f7c378e815392acd9b 100644
--- a/chrome/test/data/webui/md_downloads/layout_tests.js
+++ b/chrome/test/data/webui/md_downloads/layout_tests.js
@@ -24,5 +24,6 @@ suite('layout tests', function() {
 
     var item = manager.$$('downloads-item');
     assertLT(item.$$('#url').offsetWidth, item.offsetWidth);
+    assertEquals(300, item.$$('#url').textContent.length);
   });
 });