Follow ARIA spec guidelines for role=button with aria-pressed.

webkit/glue/webkit_strings.grd

 <?xml version="1.0" encoding="UTF-8"?>
 
 <!-- This file contains definitions of resources that will be translated for
 each locale. Specifically, these are UI strings that are used by webkit that
 need to be translated for each locale.-->
 
 <!-- Some of these strings and string descriptions were taken from
 WebKit/win/WebCoreLocalizedStrings.cpp so we include the original license
 below:
 
@@ skipping 12 matching lines @@
  * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

[jamesr, 2014/03/06 05:53:58]

this seems unrelated

[aboxhall, 2014/03/06 15:21:04]

Yeah, my editor is configured to strip trailing whitespace on save. Is it a
problem if I leave this in, or should I go fix it?

  */
 -->
 
 <grit base_dir="." latest_public_release="0" current_release="1"
       source_lang_id="en" enc_check="möl">
   <outputs>
     <!-- TODO add each of your output files.  Modify the three below, and add
     your own for your various languages.  See the user's guide
     (http://wiki/Main/GritUsersGuide) for more details.
     Note that all output references are relative to the output directory
@@ skipping 296 matching lines @@
       </message>
       <message name="IDS_AX_ROLE_HEADING" desc="accessibility role description for headings">
         heading
       </message>
       <message name="IDS_AX_ROLE_FOOTER" desc="accessibility role description for footers">
         footer
       </message>
       <message name="IDS_AX_ROLE_STEPPER" desc="accessibility role description for a stepper - a control where you can use up/down arrows to increment or decrement it. The name 'stepper' is how this user interface element is described by VoiceOver on Mac OS X; the translation should be consistent with VoiceOver.">
         stepper
       </message>
+      <message name="IDS_AX_ROLE_TOGGLE_BUTTON" desc="accessibility role description for a toggle button">
+        toggle button
+      </message>
 
       <message name="IDS_AX_BUTTON_ACTION_VERB" desc="Verb stating the action that will occur when a button is pressed, as used by accessibility.">
         press
       </message>
       <message name="IDS_AX_RADIO_BUTTON_ACTION_VERB" desc="Verb stating the action that will occur when a radio button is clicked, as used by accessibility.">
         select
       </message>
       <message name="IDS_AX_TEXT_FIELD_ACTION_VERB" desc="Verb stating the action that will occur when a text field is selected, as used by accessibility.">
         activate
       </message>
@@ skipping 324 matching lines @@
         Loading
       </message>
 
       <message name="IDS_PLUGIN_INITIALIZATION_ERROR" desc="A message displayed when a plug-in failed to load">
         Couldn't load plug-in.
       </message>
 
     </messages>
   </release>
 </grit>