Add chrome.webstore API methods to allow sites to see progress of installation

chrome/common/extensions/api/webstore.json

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 [
   {
     "namespace": "webstore",
     "description": "Use the <code>chrome.webstore</code> API to initiate app and extension installations \"inline\" from your site.",
+    "types": [
+      {
+        "id": "InstallStage",
+        "type": "string",
+        "enum": ["installing", "downloading"],
+        "description": "Enum used to indicate the stage of the installation process. 'downloading' indicates that the necessary files are being downloaded, and 'installing' indicates that the files are downloaded and are being actively installed."
+      }
+    ],  // types
     "functions": [
       {
         "name": "install",
         "allowAmbiguousOptionalArguments": true,
         "parameters": [
           {
             "name": "url",
             "type": "string",
             "optional": true,
             "description": "If you have more than one <code>&lt;link&gt;</code> tag on your page with the <code>chrome-webstore-item</code> relation, you can choose which item you'd like to install by passing in its URL here. If it is omitted, then the first (or only) link will be used. An exception will be thrown if the passed in URL does not exist on the page."
@@ skipping 12 matching lines @@
             "parameters": [
               {
                 "name": "error",
                 "type": "string",
                 "description": "The failure detail. You may wish to inspect or log this for debugging purposes, but you should not rely on specific strings being passed back."
               }
             ],
             "description": "This function is invoked when inline installation does not successfully complete. Possible reasons for this include the user canceling the dialog, the linked item not being found in the store, or the install being initiated from a non-verified site."
           }
         ]
-      }  // install
-    ]
+      },  // install
+      {
+        "name": "setInstallStageListener",

[not at google - send to devlin, 2014/02/27 21:49:56]

It's pretty weird to have these special methods. make them events to be
consistent with the rest of the platform. You'll need to construct the events
and call dispatch() or whatever the method is yourself; but that's easy enough.

[Devlin, 2014/02/28 18:04:51]

Done!  Thanks for the help on this :)

+        "description": "Set a listener function to be called whenever an inline installation enters a new InstallStage.",
+        "parameters": [
+          {
+            "name": "listener",
+            "type": "function",
+            "parameters": [
+              {
+                "name": "stage",
+                "$ref": "InstallStage",
+                "description": "The InstallStage that just began."
+              }
+            ],
+            "description": "The listener function to be called."
+          }
+        ]
+      },  // setInstallChangeListener
+      {
+        "name": "setDownloadProgressListener",
+        "description": "Set a listener function to be called with periodic download progress updates.",
+        "parameters": [
+          {
+            "name": "listener",
+            "type": "function",
+            "parameters": [
+              {
+                "name": "percentDownloaded",
+                "type": "number",
+                "description": "The percentage of the download which has been completed, between 0 and 1."

[not at google - send to devlin, 2014/02/27 21:49:56]

"percentage" is misleading. "The progress of the download. 0.0 means it hasn't
been started, 1.0 means completed" or something.

[Devlin, 2014/02/28 18:04:51]

Done.

+              }
+            ],
+            "description": "The listener function to be called."
+          }
+        ]
+      }  // setDownloadProgressListener
+    ]  // functions
   }  // webstore
 ]