Prevent duplicate webstore install requests being serviced.

chrome/test/data/extensions/api_test/webstore_private/common.js

 // 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.
 
 // The id of an extension we're using for install tests.
 var extensionId = "enfkhcelefdadlmkffamgdlgplcionje";
 
 // The id of an app we're using for install tests.
 var appId = "iladmdjkfniedhfhcfoefgojhgaiaccc";
 
@@ skipping 23 matching lines @@
   checkItemInstalled(extensionId, callback);
 }
 
 var cachedIcon = null;
 var img = null;
 
 // This returns the base64-encoded content of the extension's image.
 function getIconData(callback) {
   if (cachedIcon) {
     callback(cachedIcon);
+    return;
   }
   var canvas = document.createElement("canvas");
   canvas.style.display = "none";
   canvas.width = 128;
   canvas.height = 128;
   img = new Image();
   img.onload = function() {
     console.log('img.onload called');
     var ctx = canvas.getContext("2d");
     ctx.drawImage(img, 0, 0);
     var tmp = canvas.toDataURL();
     // Strip the data url prefix to just get the base64-encoded bytes.
     cachedIcon = tmp.slice(tmp.search(",")+1);
     callback(cachedIcon);
   };
   img.src = "extension/icon.png";
 }
 
 // This returns the string contents of the extension's manifest file.
 function getManifest(alternativePath) {
   // Do a synchronous XHR to get the manifest.
   var xhr = new XMLHttpRequest();
   xhr.open("GET",
            alternativePath ? alternativePath : "extension/manifest.json",
            false);
   xhr.send(null);
   return xhr.responseText;
 }
+
+// Installs the extension with the given |installOptions|, calls
+// |whileInstalled| and then uninstalls the extension.
+function installAndCleanUp(installOptions, whileInstalled) {
+  // Begin installing.
+  chrome.webstorePrivate.beginInstallWithManifest3(
+      installOptions,
+      callbackPass(function(result) {
+        assertNoLastError();
+        assertEq("", result);
+
+        // Now complete the installation.
+        chrome.webstorePrivate.completeInstall(
+            extensionId,
+            callbackPass(function(result) {
+              assertNoLastError();
+              assertEq(undefined, result);
+
+              whileInstalled();
+
+              chrome.management.uninstall(extensionId, {}, callbackPass());
+            }));
+      }));
+}