Split the private webstore install API into two parts....

chrome/test/data/extensions/api_test/extension_gallery_install/test.html

Index: chrome/test/data/extensions/api_test/extension_gallery_install/test.html
===================================================================
--- chrome/test/data/extensions/api_test/extension_gallery_install/test.html	(revision 65457)
+++ chrome/test/data/extensions/api_test/extension_gallery_install/test.html	(working copy)
@@ -16,7 +16,7 @@
       if (id == extension.id)
         found = true;
     });
-    
+
     callback(found);
   });
 }
@@ -26,10 +26,10 @@
   chrome.test.assertEq(false, installed);
 
   // Install "gallery" extensions.
-  chrome.management.onInstalled.addListener(function(info) {  
+  chrome.management.onInstalled.addListener(function(info) {
     chrome.test.assertEq(id, info.id);
     console.log("Installed " + info.id);
-    
+
     // Double check it is installed.
     checkInstalled(function(installed) {
       chrome.test.assertEq(true, installed);
@@ -39,7 +39,7 @@
         // And check that it's gone.
         checkInstalled(function(installed) {
           chrome.test.assertEq(false, installed);
-          
+
           chrome.test.succeed();
         });
       });
@@ -50,8 +50,17 @@
       });
     });
   });
-  chrome.webstorePrivate.install(id, function() {
+  chrome.webstorePrivate.beginInstall(id, function() {
+    if (window.location.href.indexOf("expect_error=true") > 0) {
+      chrome.test.assertEq(chrome.extension.lastError.message,
+          "This function must be called during a user gesture");
+      chrome.test.succeed();
+      return;
+    }
     chrome.test.assertNoLastError();
+    chrome.webstorePrivate.completeInstall(id, function() {

[Erik does not do reviews, 2010/11/09 16:32:21]

seems like you need a couple of tests that call completeInstall without
beginInstall or with a failed beginInstall.

[asargent_no_longer_on_chrome, 2010/11/10 00:23:48]

I've simplified this test and added others to cover the cases you suggested. 

+      chrome.test.assertNoLastError();
+    });
   });
   console.log("Installing...");
 });