Change user-facing strings in settings: "Themes" to "Theme"

This affects:
1. desktop settings
2. android settings
3. desktop sync settings

Bug: 1114258
Change-Id: Ia51d1b9684096d3d61bab5108e754fc63c87e9e3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2352039
Auto-Submit: Evan Stade <estade@chromium.org>
Commit-Queue: David Trainor <dtrainor@chromium.org>
Reviewed-by: David Trainor <dtrainor@chromium.org>
Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#799032}

chrome/app/settings_strings.grdp

@@ -107,7 +107,7 @@
   </if>
   <if expr="not chromeos">
     <message name="IDS_SETTINGS_THEMES" desc="Name of the control which allows the user to get a theme for the browser.">
-      Themes
+      Theme
     </message>
   </if>
   <if expr="is_linux and not chromeos">

chrome/app/settings_strings_grdp/IDS_SETTINGS_THEMES.png.sha1

+32c6510f7d8322ee5a73cfe1bb18db0402a7e5a1
\ No newline at end of file

chrome/app/shared_settings_strings.grdp

@@ -320,12 +320,12 @@
 
   <if expr="chromeos">
     <message name="IDS_SETTINGS_THEMES_AND_WALLPAPERS_CHECKBOX_LABEL" desc="Label for the checkbox which enables or disables syncing themes and wallpapers between multiple browser instances.">
-        Themes &amp; Wallpapers
+        Theme &amp; Wallpaper
       </message>
     </if>
   <if expr="not chromeos">
       <message name="IDS_SETTINGS_THEMES_AND_WALLPAPERS_CHECKBOX_LABEL" desc="Label for the checkbox which enables or disables syncing themes and wallpapers between multiple browser instances.">
-        Themes
+        Theme
     </message>
   </if>
 </grit-part>

chrome/app/shared_settings_strings_grdp/IDS_SETTINGS_THEMES_AND_WALLPAPERS_CHECKBOX_LABEL.png.sha1

+4e170e7f2c5a1f78d7bd45d4641058e90f65856b
\ No newline at end of file

chrome/browser/ui/android/strings/android_chrome_strings.grd

@@ -664,7 +664,7 @@ CHAR-LIMIT guidelines:
 
       <!-- Themes settings -->
       <message name="IDS_THEME_SETTINGS" desc="Title for the Theme settings. [CHAR-LIMIT=32]">
-        Themes
+        Theme
       </message>
       <message name="IDS_THEMES_SYSTEM_DEFAULT_TITLE" desc="Title for the System Default option. [CHAR-LIMIT=32]">
         System default

chrome/browser/ui/android/strings/android_chrome_strings_grd/IDS_THEME_SETTINGS.png.sha1

-4b29c5541aa913738c53a46c8bff615c56b35548
+7f7fad6d8266f8531da601aac2797181c5b878b7
\ No newline at end of file