Add an infobar if a session is being controlled by an automated test.

chrome/common/chrome_switches.cc

Index: chrome/common/chrome_switches.cc
diff --git a/chrome/common/chrome_switches.cc b/chrome/common/chrome_switches.cc
index 786179a64a5d03ddd9fc456b98ff9fc5da03bd0f..29dba93eeb6f5ad35a14fe2cf5dd4a32a54f7496 100644
--- a/chrome/common/chrome_switches.cc
+++ b/chrome/common/chrome_switches.cc
@@ -312,6 +312,9 @@ const char kEnableAddToShelf[] = "enable-add-to-shelf";
 const char kEnableAudioDebugRecordingsFromExtension[] =
     "enable-audio-debug-recordings-from-extension";
 
+// Inform users that their browser is being controlled by an automated test.
+const char kEnableAutomation[] = "enable-automation";
+
 // Enables the benchmarking extensions.
 const char kEnableBenchmarking[]            = "enable-benchmarking";