Use process_singleton_linux on Mac.

chrome/app/chromium_strings.grd

 <?xml version="1.0" encoding="UTF-8"?>
 <!-- This file contains definitions of strings that are distribution specific.
 These strings will not be translated and only english versions will
 be available for now. -->
 
 <grit base_dir="." latest_public_release="0" current_release="1"
       source_lang_id="en" enc_check="möl">
   <outputs>
     <output filename="grit/chromium_strings.h" type="rc_header">
       <emit emit_type='prepend'></emit>
@@ skipping 1097 matching lines @@
         Chromium is using your camera and microphone.
       </message>
       <message name="IDS_MEDIA_STREAM_STATUS_TRAY_TEXT_AUDIO_ONLY" desc="Tool tip for the capture status tray icon when microphone is being used">
         Chromium is using your microphone.
       </message>
       <message name="IDS_MEDIA_STREAM_STATUS_TRAY_TEXT_VIDEO_ONLY" desc="Tool tip for the capture status tray icon when camera is being used">
         Chromium is using your camera.
       </message>
 
       <!-- ProcessSingleton -->
-      <if expr="is_linux">
-        <message name="IDS_PROFILE_IN_USE_LINUX" desc="Message shown when the browser cannot start because the profile is in use on a different host.">
+      <if expr="is_posix">

[tapted, 2014/04/08 17:56:44]

This might put an unnecessary string in the android resource bundle (and I think
there's a script someone runs checking this..) - maybe is_linux or is_macosx?

[jackhou1, 2014/04/14 04:12:10]

Done.

+        <message name="IDS_PROFILE_IN_USE_POSIX" desc="Message shown when the browser cannot start because the profile is in use on a different host.">
           The profile appears to be in use by another Chromium process (<ph name="PROCESS_ID">$1<ex>12345</ex></ph>) on another computer (<ph name="HOST_NAME">$2<ex>example.com</ex></ph>). Chromium has locked the profile so that it doesn't get corrupted. If you are sure no other processes are using this profile, you can unlock the profile and relaunch Chromium.
         </message>
       </if>
 
       <!-- Mac First-run dialog messages -->
       <if expr="is_macosx">
         <message name="IDS_FIRSTRUN_DLG_MAC_SET_DEFAULT_BROWSER_LABEL" desc="Label for checkbox that sets the default browser">
           Set Chromium as your default browser
         </message>
       </if>
@@ skipping 47 matching lines @@
       </message>
       <message name="IDS_EXTENSIONS_SETTINGS_API_SECOND_LINE_START_PAGES" desc="Second line in the Settings API bubble. Only shown if the secondary change by the extension was just the start pages. The triple single quotes are needed to preserve the space before and after the sentence which is needed when the language (Chrome is being translated to) uses space as word separator. Please preserve them, unless the language being translated to does not use space as word separator.">
         ''' It also controls what page is shown when you start Chromium. '''
       </message>
       <message name="IDS_EXTENSIONS_SETTINGS_API_SECOND_LINE_START_AND_HOME" desc="Second line in the Settings API bubble. Only shown if the secondary change by the extension was both the start page and the home page. See IDS_EXTENSIONS_SETTINGS_API_SECOND_LINE_START_PAGES for reason for triple quotes.">
         ''' It also controls what page is shown when you start Chromium or click the Home button. '''
       </message>
       <message name="IDS_EXTENSIONS_SETTINGS_API_SECOND_LINE_START_AND_SEARCH" desc="Second line in the Settings API bubble. Only shown if the secondary change by the extension was both the start page and the search engine. See IDS_EXTENSIONS_SETTINGS_API_SECOND_LINE_START_PAGES for reason for triple quotes.">
         ''' It also controls what page is shown when you start Chromium or search from the Omnibox. '''
       </message>
-      
+
       <!-- Update bubble -->
       <message name="IDS_REINSTALL_APP" desc="Text for the button the user clicks to reinstall the app.">
         Reinstall Chromium
       </message>
       <if expr="use_titlecase">
         <message name="IDS_UPGRADE_BUBBLE_MENU_ITEM" desc="In Title Case: Text for the Chrome menu option replacing Update required.">
           Chromium is Out of Date
         </message>
       </if>
       <if expr="not use_titlecase">
@@ skipping 16 matching lines @@
         <message name="IDS_NEW_TAB_OTR_EXTENSIONS_MESSAGE"
                  desc="Explanation in a new OTR window that extensions have been disabled while in OTR.">
           Because Chromium does not control how extensions handle your personal data, all extensions have been disabled for incognito windows. You can reenable them individually in the
           <ph name="BEGIN_LINK">&lt;a href="$1"&gt;</ph>extensions manager<ph name="END_LINK">&lt;/a&gt;<ex>&lt;/a&gt;</ex></ph>.
         </message>
       </if>
 
     </messages>
   </release>
 </grit>