Added shadow DOM support to chromedriver. atoms.cc and .h are generated from the selenium tree. I'l…

chrome/test/chromedriver/js/focus.js

Index: chrome/test/chromedriver/js/focus.js
diff --git a/chrome/test/chromedriver/js/focus.js b/chrome/test/chromedriver/js/focus.js
index 2945a34c9a74bf93133054d544861467c64432c9..4d6961f9ef2a4eda3ec2ae9f111a648156ae3197 100644
--- a/chrome/test/chromedriver/js/focus.js
+++ b/chrome/test/chromedriver/js/focus.js
@@ -38,6 +38,24 @@ function focus(element) {
         throw error;
     }
   }
-  if (element != doc.activeElement)
+  var activeElement = doc.activeElement;
+  // If the element is in a shadow DOM, then as far as the document is concerned
+  // the shadow host is the active element. We need to go through the tree of
+  // shadow DOMs to check that the element we gave focus to is now active
+  if (element != activeElement) {
+    var shadowRoot = activeElement.shadowRoot;
+    while (shadowRoot) {
+      var activeElement = shadowRoot.activeElement;
+      if (element == activeElement) {
+        // the shadow DOM's active element is our requested element. We're good.
+        break;
+      }
+      // The shadow DOM's active element isn't our requested element, check to
+      // see if there's a nested shadow DOM.
+      shadowRoot = activeElement.shadowRoot;
+    }
+  }
+
+  if (element != activeElement)
     throw new Error('cannot focus element');
 }