Remove Chromium plumbing for fixed-position-creates-stacking-context.

chrome/app/generated_resources.grd

 <?xml version="1.0" encoding="utf-8"?>
 
 <!--
 This file contains definitions of resources that will be translated for each
 locale.  The variables is_win, is_macosx, is_linux, and is_posix are available
 for making strings OS specific.  Other platform defines such as use_titlecase
 are declared in build/common.gypi.
 -->
 
 <grit base_dir="." latest_public_release="0" current_release="1"
@@ skipping 5733 matching lines @@
         This option disables support in WebRTC for encoding video streams using platform hardware.
       </message>
       <if expr="is_android">
         <message name="IDS_FLAGS_DISABLE_WEBAUDIO_NAME" desc="Name of the 'Disable WebAudio' lab.">
           Disable WebAudio
         </message>
         <message name="IDS_FLAGS_DISABLE_WEBAUDIO_DESCRIPTION" desc="Description for the flag to disable WebAudio.">
           Enabling this option prevents web sites from accessing the WebAudio API.
         </message>
       </if>
-      <message name="IDS_FLAGS_FIXED_POSITION_CREATES_STACKING_CONTEXT_NAME" desc="Name of the 'Fixed position creates stacking context' lab.">
-        Fixed position elements create stacking contexts.
-      </message>
-      <message name="IDS_FLAGS_FIXED_POSITION_CREATES_STACKING_CONTEXT_DESCRIPTION" desc="Description for the flag to make fixed position elements create stacking contexts.">
-        Enabling this option makes all fixed position elements create new CSS stacking contexts.
-      </message>
       <message name="IDS_FLAGS_COMPOSITING_FOR_FIXED_POSITION_NAME" desc="Name of the 'Compositing for fixed position elements' lab.">
         Compositing for fixed position elements.
       </message>
       <message name="IDS_FLAGS_COMPOSITING_FOR_FIXED_POSITION_DESCRIPTION" desc="Description for the flag to make fixed position elements become composited layers.">
         Enabling this option will make fixed position elements have their own composited layers. Note that fixed position elements must also create stacking contexts for this to work.
       </message>
       <message name="IDS_FLAGS_COMPOSITING_FOR_FIXED_POSITION_HIGH_DPI" desc="Description of the 'Compositing for fixed position elements on high DPI' experiment.">
         Enabled only for high-DPI displays
       </message>
       <message name="IDS_FLAGS_COMPOSITING_FOR_TRANSITION_NAME" desc="Name of the 'Compositing for RenderLayers with transitions' lab.">
@@ skipping 8392 matching lines @@
     <message name="IDS_FLAGS_EXTENSION_CONTENT_VERIFICATION_ENFORCE" desc="Description of the 'Extension Content Verification' enforce mode">
       Enforce (try to get hashes, and enforce them if successful)
     </message>
 
     <message name="IDS_FLAGS_EXTENSION_CONTENT_VERIFICATION_ENFORCE_STRICT" desc="Description of the 'Extension Content Verification' enforce strict mode">
       Enforce strict (hard fail if we can't get hashes)
     </message>
   </messages>
   </release>
 </grit>