Polish the keybinding implementation a bit.

chrome/common/extensions/docs/static/experimental.keybinding.html

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 <p>
 The keybinding API allows you to add keyboard shortcuts that trigger actions in
 your extension. An action can be opening the browser action or page action popup
 or sending a command to the extension.
 </p>
 
 <h2 id="manifest">Manifest</h2>
 <p>
 In addition to the "experimental" permission you must declare the "keybinding"
-permission in your extension's manifest to use this API.
+permission in your extension's manifest to use this API and set manifest_version
+to (at least) 2.
 </p>
 
 <pre>{
   "name": "My extension",
   ...
 <b>  "permissions": [
     "experimental",
     "keybinding",
   ]</b>,
   ...
 }</pre>
 
 <h2 id="usage">Usage</h2>
 <p>The keybinding API allows you to define specific commands, and bind them to a
 default key combination. Each command your extension accepts must be listed in
 the manifest as an attribute of the 'commands' manifest key. Note: Combinations
 that involve Ctrl+Alt are not permitted in order to avoid conflicts with the
 AltGr key.</p>
 
 <pre>{
   "name": "My extension",
   ...
 <b>  "commands": {
     "toggle-feature-foo": {
-      "key": "Ctrl+Shift+Y",
+      "suggested_key_win": "Ctrl+Shift+Y",
+      "suggested_key_mac": "Command+Shift+Y",
+      "suggested_key_other": "Ctrl+Shift+Y",
       "description": "Toggle feature foo"
     },
-    "browserAction": {
-      "key": "Ctrl+Shift+B"
+    "_execute_browser_action": {
+      "suggested_key_win": "Ctrl+Shift+B",
+      "suggested_key_mac": "Command+Shift+B",
+      "suggested_key_other": "Ctrl+Shift+B",
     },
-    "pageAction": {
-      "key": "Alt+P"
+    "_execute_page_action": {
+      "suggested_key_win": "Alt+P",
+      "suggested_key_mac": "Option+P",
+      "suggested_key_other": "Alt+P",
     }
 
   }</b>,
   ...
 }</pre>
 
 <p>In your background page, you can bind a handler to each of the commands
-defined in the manifest (except for 'browserAction' and 'pageAction') via
-onCommand.addListener. For example:</p>
+defined in the manifest (except for '_execute_browser_action' and
+'_execute_page_action') via onCommand.addListener. For example:</p>
 
 <pre>
 chrome.experimental.keybinding.onCommand.addListener(function(command) {
   console.log('Command:', command);
 });
 </pre>
 
-<p>The 'browserAction' and 'pageAction' commands are reserved for the action of
-opening your extension's popups. They won't normally generate events that you
-can handle. If you need to take action based on your popup opening, consider
-listening for an 'onDomReady' event inside your popup's code.
+<p>The '_execute_browser_action' and '_execute_page_action' commands are
+reserved for the action of opening your extension's popups. They won't normally
+generate events that you can handle. If you need to take action based on your
+popup opening, consider listening for an 'onDomReady' event inside your popup's
+code.
 </p>
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