Don't require expectations file for DumpAccessibility tests.

content/test/BUILD.gn

Index: content/test/BUILD.gn
diff --git a/content/test/BUILD.gn b/content/test/BUILD.gn
index 32828ed3b2e728041f710db825902112ca4a2c7a..3bfc5d89d70291ae045fea31b542298960a3c219 100644
--- a/content/test/BUILD.gn
+++ b/content/test/BUILD.gn
@@ -436,11 +436,6 @@ test("content_browsertests") {
     libs = [ "oleacc.lib" ]
   }
 
-  if (is_linux) {
-    sources -=
-        [ "../browser/accessibility/dump_accessibility_tree_browsertest.cc" ]
-  }
-
   if (is_android) {
     sources += rebase_path(
             content_tests_gypi_values.content_browsertests_android_sources,