Enable tests related to the extensions web ui that were flaky.

chrome/browser/ui/webui/extensions/extension_settings_browsertest.js

Index: chrome/browser/ui/webui/extensions/extension_settings_browsertest.js
diff --git a/chrome/browser/ui/webui/extensions/extension_settings_browsertest.js b/chrome/browser/ui/webui/extensions/extension_settings_browsertest.js
index 8183dc84cac804e3b2b14191ee045603b73a5346..a1b40e9ae3fe0f08b12ff589c49980a90f071a0b 100644
--- a/chrome/browser/ui/webui/extensions/extension_settings_browsertest.js
+++ b/chrome/browser/ui/webui/extensions/extension_settings_browsertest.js
@@ -49,14 +49,7 @@ ExtensionSettingsWebUITest.prototype = {
 
   /** @override */
   setUp: function() {
-    // Make all transitions take 0ms for testing purposes.
-    var noTransitionStyle = document.createElement('style');
-    noTransitionStyle.textContent =
-        '* {' +
-        '  -webkit-transition-duration: 0ms !important;' +
-        '  -webkit-transition-delay: 0ms !important;' +
-        '}';
-    document.querySelector('head').appendChild(noTransitionStyle);
+    this.disableAnimationsAndTransitions();
   },
 
   /**
@@ -114,7 +107,7 @@ ExtensionSettingsWebUITest.prototype = {
                   this.verifyDeveloperModeWorks,
                   testDone];
     this.nextStep();
-  }
+  },
 };
 
 // Verify that developer mode doesn't change behavior when the number of
@@ -251,8 +244,7 @@ AsyncExtensionSettingsWebUITest.prototype = {
 };
 
 // Often times out on all platforms: http://crbug.com/467528
-TEST_F('AsyncExtensionSettingsWebUITest',
-       'DISABLED_testErrorListButtonVisibility',
+TEST_F('AsyncExtensionSettingsWebUITest', 'testErrorListButtonVisibility',
     function() {
   var testButtonVisibility = function() {
     // 2 extensions are loaded:
@@ -262,15 +254,17 @@ TEST_F('AsyncExtensionSettingsWebUITest',
     //     This means 2 buttons: 1 visible and 1 hidden.
     var visibleButtons = document.querySelectorAll(
         '.extension-error-list-show-more > a:not([hidden])');
-    assertEquals(1, visibleButtons.length);
+    expectEquals(1, visibleButtons.length);
     // Visible buttons must be part of the focusRow.
-    assertTrue(visibleButtons[0].hasAttribute('column-type'));
+    expectTrue(visibleButtons[0] &&
+               visibleButtons[0].hasAttribute('column-type'));
 
     var hiddenButtons = document.querySelectorAll(
         '.extension-error-list-show-more > a[hidden]');
-    assertEquals(1, hiddenButtons.length);
+    expectEquals(1, hiddenButtons.length);
     // Hidden buttons must NOT be part of the focusRow.
-    assertFalse(hiddenButtons[0].hasAttribute('column-type'));
+    expectFalse(hiddenButtons[0] &&
+                hiddenButtons[0].hasAttribute('column-type'));
 
     this.nextStep();
   };