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

chrome/common/extensions/api/webstore.json

Index: chrome/common/extensions/api/webstore.json
diff --git a/chrome/common/extensions/api/webstore.json b/chrome/common/extensions/api/webstore.json
index 31cbd2d01239d79f5abb53706727928da82a6cd2..f7d8154ab720207ef895a5e1383294ed60c56cec 100644
--- a/chrome/common/extensions/api/webstore.json
+++ b/chrome/common/extensions/api/webstore.json
@@ -6,6 +6,40 @@
   {
     "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
+    "events": [
+      {
+        "name": "onInstallStageChanged",
+        "description": "Fired when an inline installation enters a new InstallStage.",
+        "type": "function",
+        "parameters": [
+          {
+            "name": "stage",
+            "$ref": "InstallStage",
+            "description": "The InstallStage that just began."
+          }
+        ]

[asargent_no_longer_on_chrome, 2014/03/03 18:49:08]

For future proofing if we ever decided to allow multiple concurrent
installations, would it make sense to have these events also communicate the
installId that gets generated inside the implementation of webstore.install()?
That also might mean we'd want to return that id from install(), which we don't
currently. 

[Devlin, 2014/03/03 21:15:13]

I was wondering about that as well.  If we ever do allow multiple installs, it
makes sense, but otherwise it just seems like exposing implementation that
should be exposed - so I don't know.  Ben (as author of the js bindings),
thoughts?

[asargent_no_longer_on_chrome, 2014/03/03 22:25:33]

Yeah, it would probably be ok to leave this for a follow-up. 

+      },  // onInstallStageChanged
+      {
+        "name": "onDownloadProgress",
+        "description": "Fired periodically with the download progress of an inline install.",
+        "type": "function",
+        "parameters": [
+          {
+            "name": "percentDownloaded",
+            "type": "number",
+            "description": "The progress of the download, between 0 and 1. 0 indicates no progress; 1.0 indicates complete."
+          }
+        ]
+      }  // onDownloadProgress
+    ],  // events
     "functions": [
       {
         "name": "install",
@@ -39,6 +73,6 @@
           }
         ]
       }  // install
-    ]
+    ]  // functions
   }  // webstore
 ]