Introduce a stable set of errors for inline install

chrome/browser/apps/ephemeral_app_launcher_browsertest.cc

 // Copyright 2014 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.
 
 #include "base/message_loop/message_loop_proxy.h"
 #include "chrome/browser/apps/ephemeral_app_launcher.h"
 #include "chrome/browser/extensions/extension_install_checker.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/extensions/extension_test_message_listener.h"
 #include "chrome/browser/extensions/install_tracker.h"
@@ skipping 118 matching lines @@
   mutable bool install_initiated_;
   std::string requirements_check_error_;
   bool install_prompt_created_;
 };
 
 class LaunchObserver {
  public:
   LaunchObserver()
       : done_(false),
         waiting_(false),
-        result_(webstore_install::UNKNOWN_ERROR) {}
+        result_(webstore_install::OTHER_ERROR) {}
 
   webstore_install::Result result() const { return result_; }
   const std::string& error() const { return error_; }
 
   void OnLaunchCallback(webstore_install::Result result,
                         const std::string& error) {
     result_ = result;
     error_ = error;
     done_ = true;
     if (waiting_) {
@@ skipping 388 matching lines @@
 }
 
 // Verifies that a launch will fail if a duplicate launch is in progress.
 IN_PROC_BROWSER_TEST_F(EphemeralAppLauncherTest, DuplicateLaunchInProgress) {
   extensions::ActiveInstallData install_data(kDefaultAppId);
   install_data.is_ephemeral = true;
   InstallTracker::Get(profile())->AddActiveInstall(install_data);
 
   RunLaunchTest(kDefaultAppId, webstore_install::LAUNCH_IN_PROGRESS, false);
 }