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..fe3ed26fa05a65c46b07672ebab75bd94b3b33c7 100644
--- a/chrome/common/extensions/api/webstore.json
+++ b/chrome/common/extensions/api/webstore.json
@@ -6,6 +6,14 @@
   {
     "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",
@@ -38,7 +46,43 @@
             "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",
+        "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."
+              }
+            ],
+            "description": "The listener function to be called."
+          }
+        ]
+      }  // setDownloadProgressListener
+    ]  // functions
   }  // webstore
 ]