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 73bc4215bc96e4faca88d9129c201f2592577208..b0d7e66531e9e158533dc76889b343b08e2bc0d0 100644
--- a/chrome/common/chrome_switches.cc
+++ b/chrome/common/chrome_switches.cc
@@ -304,6 +304,9 @@ 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";