[ChromeDriver] Remove FrameTracker's dependency on DomTracker.

chrome/test/chromedriver/frame_tracker.cc

Index: chrome/test/chromedriver/frame_tracker.cc
diff --git a/chrome/test/chromedriver/frame_tracker.cc b/chrome/test/chromedriver/frame_tracker.cc
index dd1786272724a685489c50efc731a04c11167c2c..e03c105a998167248ca7a5eae484abab736b450a 100644
--- a/chrome/test/chromedriver/frame_tracker.cc
+++ b/chrome/test/chromedriver/frame_tracker.cc
@@ -38,7 +38,10 @@ Status FrameTracker::GetContextIdForFrame(
 Status FrameTracker::OnConnected() {
   // Enable runtime events to allow tracking execution context creation.
   base::DictionaryValue params;
-  return client_->SendCommand("Runtime.enable", params);
+  Status status = client_->SendCommand("Runtime.enable", params);
+  if (status.IsError())
+    return status;
+  return client_->SendCommand("DOM.getDocument", params);
 }
 
 void FrameTracker::OnEvent(const std::string& method,