Add docs for chrome.wallpaper API

BUG=176183

Review URL: https://codereview.chromium.org/27335003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235758 0039d316-1c4b-4281-b951-d872f2087c98

chrome/common/extensions/api/wallpaper.json

@@ -9,13 +9,12 @@
       "implemented_in": "chrome/browser/chromeos/extensions/wallpaper_api.h"
     },
     "platforms": ["chromeos"],
-    "description": "none",
+    "description": "Use the <code>chrome.wallpaper</code> API to change the ChromeOS wallpaper.",
     "functions": [
     {
       "name": "setWallpaper",
       "type": "function",
-      "description": "Sets wallpaper to the image from url with specified layout",
-      "nodoc": "true",
+      "description": "Sets wallpaper to the image at <em>url</em> or <em>wallpaperData</em> with the specified <em>layout</em>",
       "parameters": [
         {
           "name": "details",
@@ -29,7 +28,7 @@
             "url": {
               "type": "string",
               "optional": true,
-              "description": "The url of online wallpaper."
+              "description": "The URL of the wallpaper to be set."
             },
             "layout": {
               "type": "string",
@@ -38,7 +37,7 @@
             },
             "name": {
               "type": "string",
-              "description": "The file name of saved wallpaper."
+              "description": "The file name of the saved wallpaper."
             },
             "thumbnail": {
               "type": "boolean",
@@ -54,7 +53,8 @@
             {
               "type": "binary",
               "optional": true,
-              "name": "thumbnail"
+              "name": "thumbnail",
+              "description": "The jpeg encoded wallpaper thumbnail. It is generated by resizing the wallpaper to 128x60."
             }
           ]
         }

chrome/common/extensions/docs/templates/intros/wallpaper.html

+<h2 id="manifest">Manifest</h2>
+<p>You must declare the "wallpaper" permission in the app
+<a href="manifest.html">manifest</a> to use the wallpaper API.
+For example:</p>
+<pre data-filename="manifest.json">
+{
+  "name": "My extension",
+  ...
+  <b>"permissions": [
+    "wallpaper"
+  ]</b>,
+  ...
+}</pre>
+
+<h2 id="overview-examples">Examples</h2>
+
+<p>
+For example, to set the wallpaper as the image at
+<code>http://example.com/a_file.png</code>, you can call
+<code>chrome.wallpaper.setWallpaper</code> this way:
+</p>
+
+<pre>
+chrome.wallpaper.setWallpaper(
+    {
+      'url': 'http://example.com/a_file.jpg',
+      'layout': 'CENTER_CROPPED',
+      'name': 'test_wallpaper'
+    }, function() {});
+</pre>

chrome/common/extensions/docs/templates/public/apps/wallpaper.html

+{{+partials.standard_extensions_api api:apis.wallpaper intro:intros.wallpaper/}}