Set more consistent conditionals for the use mash flag

chrome/app/generated_resources.grd

Index: chrome/app/generated_resources.grd
diff --git a/chrome/app/generated_resources.grd b/chrome/app/generated_resources.grd
index 77a1be941b4eeda1651926fe63e3b5576e3aac86..d33e032aa41ec4ee45551e13e84ea46696186394 100644
--- a/chrome/app/generated_resources.grd
+++ b/chrome/app/generated_resources.grd
@@ -5790,14 +5790,14 @@ Keep your key file in a safe place. You will need it to create new versions of y
       <message name="IDS_FLAGS_REDUCED_REFERRER_GRANULARITY_DESCRIPTION" desc="Description for the flag to reduce referer granularity.">
         If a page hasn't set an explicit referrer policy, setting this flag will reduce the amount of information in the 'referer' header for cross-origin requests.
       </message>
+      <message name="IDS_FLAGS_USE_MASH_NAME" desc="Name for the flag to enable the new UI service.">

[mfomitchev, 2017/02/10 14:37:47]

We probably don't want to have this string in builds that don't have
ENABLE_PACKAGE_MASH_SERVICES enabled.
It's probably okay to just move the flag inside the CrOS #ifdef - I don't
imagine we care too much about this flag being present in about:flags UI on
non-CrOS. At the time I wrote my CL I wasn't sure if we would ever want to turn
ENABLE_PACKAGE_MASH_SERVICES off on CrOS, but sky@ has since clarified we don't
have to worry about that either. So I am inclined to move the flag definition
back.

The alternative would be to add enable_package_mash_services to
chrome_grit_defines and use it here. That would be fine, but it's a bit more
cruft, and it seems unnecessary to me.

+        Mojo UI Service (mus).
+      </message>
+      <message name="IDS_FLAGS_USE_MASH_DESCRIPTION" desc="Description for the flag to enable the new UI service.">
+        Enable mus, mash etc.
+      </message>
 
       <if expr="chromeos">
-        <message name="IDS_FLAGS_USE_MASH_NAME" desc="Name for the flag to enable the new UI service.">
-          Mojo UI Service (mus).
-        </message>
-        <message name="IDS_FLAGS_USE_MASH_DESCRIPTION" desc="Description for the flag to enable the new UI service.">
-          Enable mus, mash etc.
-        </message>
         <message name="IDS_FLAGS_ALLOW_TOUCHPAD_THREE_FINGER_CLICK_NAME" desc="Name for the flag to enable touchpad three finger click as middle button.">
           Touchpad three-finger-click
         </message>