Remove use_ash from resource grd files

We have not shipped Windows Ash for years. There is a 1:1 mapping
between "use_ash" and "chromeos", so consolidate them.

TBR=oshima@chromium.org for theme_resources.grd

Bug: 673826
Test: compiles, bots
Change-Id: If76122c1089cde2ec2b7d8822a4ca0adde25e5f3
Reviewed-on: https://chromium-review.googlesource.com/699663Reviewed-by: James Cook <jamescook@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: James Cook <jamescook@chromium.org>
Cr-Commit-Position: refs/heads/master@{#506508}

chrome/app/generated_resources.grd

@@ -1882,7 +1882,7 @@ From <ph name="DOWNLOAD_DOMAIN">$3<ex>example.com</ex></ph>
       </message>
 
       <!-- Bookmark app bubble -->
-      <if expr="use_ash">
+      <if expr="chromeos">
         <message name="IDS_ADD_TO_OS_LAUNCH_SURFACE_BUBBLE_TITLE" desc="Title of the bubble for adding a bookmark app to the shelf.">
           Add to shelf
         </message>
@@ -1892,7 +1892,7 @@ From <ph name="DOWNLOAD_DOMAIN">$3<ex>example.com</ex></ph>
           Add to Applications
         </message>
       </if>
-      <if expr="not use_ash and not is_macosx">
+      <if expr="not chromeos and not is_macosx">
         <message name="IDS_ADD_TO_OS_LAUNCH_SURFACE_BUBBLE_TITLE" desc="Title of the bubble for adding a bookmark app to the desktop.">
           Add to desktop
         </message>
@@ -1922,7 +1922,7 @@ From <ph name="DOWNLOAD_DOMAIN">$3<ex>example.com</ex></ph>
       </if>
 
       <!-- "Create application shortcuts" menu item -->
-      <if expr="use_ash">
+      <if expr="chromeos">
         <message name="IDS_ADD_TO_OS_LAUNCH_SURFACE" desc="Button text for adding a bookmark app to the shelf.">
           Add to shelf...
         </message>
@@ -1932,7 +1932,7 @@ From <ph name="DOWNLOAD_DOMAIN">$3<ex>example.com</ex></ph>
           Add to Applications...
         </message>
       </if>
-      <if expr="not use_ash and not is_macosx">
+      <if expr="not chromeos and not is_macosx">
         <message name="IDS_ADD_TO_OS_LAUNCH_SURFACE" desc="Button text for adding a bookmark app to the desktop.">
           Add to desktop...
         </message>
@@ -8724,7 +8724,7 @@ Please help our engineers fix this problem. Tell us what happened right before y
       <message name="IDS_SYNC_ERROR_USER_MENU_CONFIRM_SYNC_SETTINGS_BUTTON" desc="Button in the header of desktop user menu prompting users to confirm their sync settings.">
         Open settings
       </message>
-      <if expr="use_ash">
+      <if expr="chromeos">
         <message name="IDS_SYNC_NOTIFICATION_ACCEPT" desc="A button label shown in the sync error notification when the passphrase needs to be updated.">
           Update sync passphrase
         </message>
@@ -10414,8 +10414,8 @@ Please check your email at <ph name="ACCOUNT_EMAIL">$2<ex>jane.doe@gmail.com</ex
         </message>
       </if>
 
-      <!-- Aura strings -->
-      <if expr="use_ash">
+      <!-- Shelf strings -->
+      <if expr="chromeos">
         <message name="IDS_LAUNCHER_CONTEXT_MENU_CLOSE" desc="Title text for the 'close' context menu item of the launcher">
           Close
         </message>

chrome/app/theme/theme_resources.grd

@@ -252,7 +252,7 @@
         <structure type="chrome_scaled_image" name="IDR_NEWTAB_CHROME_WELCOME_PAGE_THUMBNAIL" file="common/ntp_welcome_thumb.png" />
       </if>
       <structure type="chrome_scaled_image" name="IDR_NEWTAB_WEBSTORE_THUMBNAIL" file="ntp_webstore_thumb.png" />
-      <if expr="use_ash">
+      <if expr="chromeos">
         <structure type="chrome_scaled_image" name="IDR_NOTIFICATION_ALERT" file="common/notification_alert.png" />
       </if>
       <if expr="chromeos">

tools/grit/grit_rule.gni

@@ -163,13 +163,6 @@ if (use_aura) {
   ]
 }
 
-if (use_ash) {
-  grit_defines += [
-    "-D",
-    "use_ash",
-  ]
-}
-
 if (use_nss_certs) {
   grit_defines += [
     "-D",