Add options for audio/video autoplay to chrome://settings/content.

chrome/app/theme/theme_resources.grd

 <?xml version="1.0" encoding="utf-8"?>
 <!-- This grd file contains images that are pre-scaled for device scale
      factors. The image returned by |base::ResourceBundle::GetImageNamed|
      will contain multiple |gfx:ImageSkiaReps| for each scale factors. The
      |fallback_to_low_resolution| attribute controls behavior when
      an image file is missing for target scale factor. If true, chrome
      will automatically scale the 1x image to the target scale factor.
      If false, build will fail due to missing resources. This is
      currently set to true for all resources, but the default will
      become false in near future.
@@ skipping 16 matching lines @@
       <!-- KEEP THESE IN ALPHABETICAL ORDER!  DO NOT ADD TO RANDOM PLACES JUST
            BECAUSE YOUR RESOURCES ARE FUNCTIONALLY RELATED OR FALL UNDER THE
            SAME CONDITIONALS. -->
       <structure type="chrome_scaled_image" name="IDR_ACCESSED_COOKIES" file="common/accessed_cookies.png" />
       <structure type="chrome_scaled_image" name="IDR_ALLOWED_CAMERA" file="common/allowed_camera.png" />
       <structure type="chrome_scaled_image" name="IDR_ALLOWED_DOWNLOADS" file="common/allowed_downloads.png" />
       <structure type="chrome_scaled_image" name="IDR_ALLOWED_FULLSCREEN" file="common/allowed_fullscreen.png" />
       <structure type="chrome_scaled_image" name="IDR_ALLOWED_IMAGES" file="common/allowed_images.png" />
       <structure type="chrome_scaled_image" name="IDR_ALLOWED_JAVASCRIPT" file="common/allowed_script.png" />
       <structure type="chrome_scaled_image" name="IDR_ALLOWED_LOCATION" file="common/allowed_location.png" />
+      <!-- TODO(dalecurtis): Add images for allowed auotplay. -->

[felt, 2015/10/28 07:52:45]

nit: s/auotplay/autoplay
(same below too)

+      <structure type="chrome_scaled_image" name="IDR_ALLOWED_MEDIA_AUTOPLAY" file="common/allowed_images.png" />
       <structure type="chrome_scaled_image" name="IDR_ALLOWED_MIC" file="common/allowed_mic.png" />
       <structure type="chrome_scaled_image" name="IDR_ALLOWED_MIDI_SYSEX" file="common/allowed_midi.png" />
       <structure type="chrome_scaled_image" name="IDR_ALLOWED_MOUSE_CURSOR" file="common/allowed_mouse_cursor.png" />
       <structure type="chrome_scaled_image" name="IDR_ALLOWED_NOTIFICATION" file="common/allowed_notifications.png" />
       <if expr="enable_plugins">
         <structure type="chrome_scaled_image" name="IDR_ALLOWED_PLUGINS" file="common/allowed_plugins.png" />
       </if>
       <structure type="chrome_scaled_image" name="IDR_ALLOWED_POPUPS" file="common/allowed_popups.png" />
       <if expr="enable_app_list and is_win and not _google_chrome">
         <structure type="chrome_scaled_image" name="IDR_APP_LIST" file="chromium/app_list_48.png" />
@@ skipping 61 matching lines @@
         <structure type="chrome_scaled_image" name="IDR_BACK_D" file="common/browser_back_disabled.png" />
         <structure type="chrome_scaled_image" name="IDR_BACK_H" file="common/browser_back_hover.png" />
         <structure type="chrome_scaled_image" name="IDR_BACK_P" file="common/browser_back_pressed.png" />
       </if>
       <structure type="chrome_scaled_image" name="IDR_BLOCKED_CAMERA" file="common/blocked_camera.png" />
       <structure type="chrome_scaled_image" name="IDR_BLOCKED_COOKIES" file="common/blocked_cookies.png" />
       <structure type="chrome_scaled_image" name="IDR_BLOCKED_DOWNLOADS" file="common/blocked_downloads.png" />
       <structure type="chrome_scaled_image" name="IDR_BLOCKED_IMAGES" file="common/blocked_images.png" />
       <structure type="chrome_scaled_image" name="IDR_BLOCKED_JAVASCRIPT" file="common/blocked_script.png" />
       <structure type="chrome_scaled_image" name="IDR_BLOCKED_LOCATION" file="common/blocked_location.png" />
+      <!-- TODO(dalecurtis): Add images for blocked auotplay. -->
+      <structure type="chrome_scaled_image" name="IDR_BLOCKED_MEDIA_AUTOPLAY" file="common/blocked_images.png" />
       <structure type="chrome_scaled_image" name="IDR_BLOCKED_MIC" file="common/blocked_mic.png" />
       <structure type="chrome_scaled_image" name="IDR_BLOCKED_MIDI_SYSEX" file="common/blocked_midi.png" />
       <structure type="chrome_scaled_image" name="IDR_BLOCKED_MIXED_CONTENT" file="common/blocked_mixed_content.png" />
       <structure type="chrome_scaled_image" name="IDR_BLOCKED_MOUSE_CURSOR" file="common/blocked_mouse_cursor.png" />
       <structure type="chrome_scaled_image" name="IDR_BLOCKED_NOTIFICATION" file="common/blocked_notifications.png" />
       <if expr="enable_plugins">
         <structure type="chrome_scaled_image" name="IDR_BLOCKED_PLUGINS" file="common/blocked_plugins.png" />
       </if>
       <structure type="chrome_scaled_image" name="IDR_BLOCKED_POPUPS" file="common/blocked_popups.png" />
       <structure type="chrome_scaled_image" name="IDR_BLOCKED_PPAPI_BROKER" file="common/blocked_pepper_broker.png" />
@@ skipping 897 matching lines @@
       <!-- People search images -->
       <structure type="chrome_scaled_image" name="IDR_PEOPLE_SEARCH_ACTION_EMAIL" file="common/mail.png" />
       <structure type="chrome_scaled_image" name="IDR_PEOPLE_SEARCH_ACTION_EMAIL_HOVER" file="common/mail_hover.png" />
       <structure type="chrome_scaled_image" name="IDR_PEOPLE_SEARCH_ACTION_EMAIL_PRESSED" file="common/mail_pressed.png" />
       <structure type="chrome_scaled_image" name="IDR_PEOPLE_SEARCH_ACTION_CHAT" file="common/chat.png" />
       <structure type="chrome_scaled_image" name="IDR_PEOPLE_SEARCH_ACTION_CHAT_HOVER" file="common/chat_hover.png" />
       <structure type="chrome_scaled_image" name="IDR_PEOPLE_SEARCH_ACTION_CHAT_PRESSED" file="common/chat_pressed.png" />
     </structures>
   </release>
 </grit>