chromeos: Adds --mus flag

chrome/browser/flag_descriptions.cc

Index: chrome/browser/flag_descriptions.cc
diff --git a/chrome/browser/flag_descriptions.cc b/chrome/browser/flag_descriptions.cc
index 635a4c38fd2b0aee8933d8c8015ad997a4057e94..7af311b700b0a5537953bc1c75050a2f8a5125c6 100644
--- a/chrome/browser/flag_descriptions.cc
+++ b/chrome/browser/flag_descriptions.cc
@@ -915,9 +915,14 @@ const char kReducedReferrerGranularityDescription[] =
 
 #if defined(OS_CHROMEOS)
 
-const char kUseMashName[] = "Mojo UI Service (mus).";
+const char kUseMusDescription[] = "Enable the Mojo UI service.";
 
-const char kUseMashDescription[] = "Enable mus, mash etc.";
+const char kUseMusName[] = "Mus";
+
+const char kEnableMashDescription[] =
+    "Mash (Chrome and ash in separate services)";

[James Cook, 2017/05/15 16:49:18]

How about:

Mash (UI, Chrome and ash in separate services)

Mus (UI in separate service, Chrome and ash in same service)

optionally: s/service/process/

I think we should emphasize that the point of these flags is the UI service
running out of process.

[sky, 2017/05/15 17:53:39]

Done.
I didn't change service to process as the important thing is they are separate
services. This may matter if we play with what processes the services actually
live in.

+
+const char kEnableMusDescription[] = "Mus (Chrome and ash in the same service)";
 
 const char kAllowTouchpadThreeFingerClickName[] = "Touchpad three-finger-click";