Add unzip.js instead of using 7za.exe. It greatly reduces the depot_tools.zip...

bootstrap/win/win_tools.bat

 @echo off
 :: Copyright (c) 2009 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.
 
 :: This script will try to find if svn and python are accessible and it not,
 :: it will try to download it and 'install' it in depot_tools.
 
 :: Sadly, we can't use SETLOCAL here otherwise it ERRORLEVEL is not correctly
 :: returned.
 
 set WIN_TOOLS_ROOT_URL=http://src.chromium.org/svn/trunk/tools
 set WIN_TOOLS_ROOT_DIR=%~dp0..\..
 
 :SVN_CHECK
 :: If the batch file exists, skip the svn check.
 if exist "%WIN_TOOLS_ROOT_DIR%\svn.bat" goto :PYTHON_CHECK
 call svn --version 2>nul 1>nul
 if errorlevel 1 goto :SVN_INSTALL
 goto :PYTHON_CHECK
 
 
 :SVN_INSTALL
 echo Installing subversion ...
 :: svn is not accessible; check it out and create 'proxy' files.
 if exist "%~dp0svn.7z" del "%~dp0svn.7z"
-cscript //nologo //e:jscript "%~dp0get_file.js" %WIN_TOOLS_ROOT_URL%/third_party/svn_win_client.7z "%~dp0svn.7z"
+cscript //nologo //e:jscript "%~dp0get_file.js" %WIN_TOOLS_ROOT_URL%/third_party/svn_win_client.zip "%~dp0svn.zip"
 if errorlevel 1 goto :SVN_FAIL
-echo call "%~dp07za" x -y "%~dp0svn.7z" -o"%WIN_TOOLS_ROOT_DIR%" 1>nul
-call "%~dp07za" x -y "%~dp0svn.7z" -o"%WIN_TOOLS_ROOT_DIR%" 1>nul
+cscript //nologo //e:jscript "%~dp0unzip.js" "%~dp0svn.zip" "%WIN_TOOLS_ROOT_DIR%"
 if errorlevel 1 goto :SVN_FAIL
 if not exist "%WIN_TOOLS_ROOT_DIR%\svn\." goto :SVN_FAIL
-del "%~dp0svn.7z"
+del "%~dp0svn.zip"
 :: Create the batch file.
 call copy /y "%~dp0svn.bat" "%WIN_TOOLS_ROOT_DIR%\svn.bat" 1>nul
 goto :PYTHON_CHECK
 
 
 :SVN_FAIL
 echo ... Failed to checkout svn automatically.
 echo Please visit http://subversion.tigris.org to download the latest subversion client
 echo before continuing.
 echo You can also get the "prebacked" version used at %WIN_TOOLS_ROOT_URL%/third_party/
@@ skipping 32 matching lines @@
 goto :END
 
 
 :returncode
 set WIN_TOOLS_ROOT_URL=
 set WIN_TOOLS_ROOT_DIR=
 exit /b %ERRORLEVEL%
 
 :END
 call :returncode %ERRORLEVEL%