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

chrome/test/webdriver/webdriver_automation.h

Index: chrome/test/webdriver/webdriver_automation.h
diff --git a/chrome/test/webdriver/webdriver_automation.h b/chrome/test/webdriver/webdriver_automation.h
index aa4c79a020db1520c16aae250d5879b75cc04762..d437a05ec38a2736d9aac02b5cd36a17c781037b 100644
--- a/chrome/test/webdriver/webdriver_automation.h
+++ b/chrome/test/webdriver/webdriver_automation.h
@@ -42,9 +42,22 @@ class Automation {
     BrowserOptions();
     ~BrowserOptions();
 
+    // The command line to use for launching the browser. If no program is
+    // specified, the default browser executable will be used.
     CommandLine command;
+
+    // The user data directory to be copied and used. If empty, a temporary
+    // directory will be used.
     FilePath user_data_dir;
+
+    // The channel ID of an already running browser to connect to. If empty,
+    // the browser will be launched with an anonymous channel.
     std::string channel_id;
+
+    // True if the Chrome process should only be terminated if quit is called.
+    // If false, Chrome will also be terminated if this process is killed or
+    // shutdown.
+    bool detach_process;
   };
 
   Automation();