chrome: Add support for custom crosh command.

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 1897585cadb46a58f6597b20bc8122d3f37c4e9c..62a2589851805d6a318128bc01614b986de1b5a4 100644
--- a/chrome/common/chrome_switches.cc
+++ b/chrome/common/chrome_switches.cc
@@ -980,6 +980,9 @@ const char kWebApkServerUrl[] = "webapk-server-url";
 #if defined(OS_CHROMEOS)
 // Enables native cups integration
 const char kEnableNativeCups[] = "enable-native-cups";
+
+// Custom crosh command.
+const char kCroshCommand[] = "crosh-command";
 #endif  // defined(OS_CHROMEOS)
 
 #if defined(USE_ASH)