[chromedriver] Add chrome.detach option for configuring Chrome not to quit

chrome/test/webdriver/webdriver_session.cc

Index: chrome/test/webdriver/webdriver_session.cc
diff --git a/chrome/test/webdriver/webdriver_session.cc b/chrome/test/webdriver/webdriver_session.cc
index efd7b1ef6e6d651550b9e9430c5937a893250ee3..6578a400adc3a7a4ea43b6dcc3779a116ef8c247 100644
--- a/chrome/test/webdriver/webdriver_session.cc
+++ b/chrome/test/webdriver/webdriver_session.cc
@@ -93,15 +93,20 @@ Error* Session::Init(const Automation::BrowserOptions& options) {
 }
 
 Error* Session::BeforeExecuteCommand() {
+  Error* error = AfterExecuteCommand();
+  if (!error) {
+    error = SwitchToTopFrameIfCurrentFrameInvalid();
+  }
+  return error;
+}
+
+Error* Session::AfterExecuteCommand() {
   Error* error = NULL;
   if (!options_.load_async) {
     LOG(INFO) << "Waiting for the page to stop loading";
     error = WaitForAllTabsToStopLoading();
     LOG(INFO) << "Done waiting for the page to stop loading";
   }
-  if (!error) {
-    error = SwitchToTopFrameIfCurrentFrameInvalid();
-  }
   return error;
 }