Use an infobar instead of alert box for extension install error.

chrome/browser/extensions/crx_installer.h

 // 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.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_CRX_INSTALLER_H_
 #define CHROME_BROWSER_EXTENSIONS_CRX_INSTALLER_H_
 #pragma once
 
 #include <string>
 
 #include "base/compiler_specific.h"
 #include "base/file_path.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/version.h"
+#include "chrome/browser/extensions/crx_installer_error.h"
 #include "chrome/browser/extensions/extension_install_prompt.h"
 #include "chrome/browser/extensions/sandboxed_extension_unpacker.h"
 #include "chrome/browser/extensions/webstore_installer.h"
 #include "chrome/common/extensions/extension.h"
 #include "chrome/common/string_ordinal.h"
 #include "chrome/common/web_apps.h"
 
 class ExtensionService;
 class SkBitmap;
 
@@ skipping 153 matching lines @@
   virtual ~CrxInstaller();
 
   // Converts the source user script to an extension.
   void ConvertUserScriptOnFileThread();
 
   // Converts the source web app to an extension.
   void ConvertWebAppOnFileThread(const WebApplicationInfo& web_app);
 
   // Called after OnUnpackSuccess as a last check to see whether the install
   // should complete.
-  bool AllowInstall(const extensions::Extension* extension, string16* error);
+  CrxInstallerError AllowInstall(const extensions::Extension* extension);
 
   // SandboxedExtensionUnpackerClient
   virtual void OnUnpackFailure(const string16& error_message) OVERRIDE;
   virtual void OnUnpackSuccess(const FilePath& temp_dir,
                                const FilePath& extension_dir,
                                const base::DictionaryValue* original_manifest,
                                const extensions::Extension* extension) OVERRIDE;
 
   // Returns true if we can skip confirmation because the install was
   // whitelisted.
   bool CanSkipConfirmation();
 
   // Runs on the UI thread. Confirms with the user (via ExtensionInstallPrompt)
   // that it is OK to install this extension.
   void ConfirmInstall();
 
   // Runs on File thread. Install the unpacked extension into the profile and
   // notify the frontend.
   void CompleteInstall();
 
   // Result reporting.
-  void ReportFailureFromFileThread(const string16& error);
-  void ReportFailureFromUIThread(const string16& error);
+  void ReportFailureFromFileThread(const CrxInstallerError& error);
+  void ReportFailureFromUIThread(const CrxInstallerError& error);
   void ReportSuccessFromFileThread();
   void ReportSuccessFromUIThread();
   void NotifyCrxInstallComplete(const extensions::Extension* extension);
 
   // The file we're installing.
   FilePath source_file_;
 
   // The URL the file was downloaded from.
   GURL download_url_;
 
@@ skipping 110 matching lines @@
   // indicate to the client whether the file should be removed and any UI
   // initiating the installation can be removed. This is different than whether
   // there was an error; if there was an error that rejects installation we
   // still consider the installation 'handled'.
   bool did_handle_successfully_;
 
   DISALLOW_COPY_AND_ASSIGN(CrxInstaller);
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_CRX_INSTALLER_H_