webrtc博客，http://www.cnblogs.com/Leo_wl/p/5706038.html
I am using one Shadowsocks proxy in China because of the GFW.  
The following is my complete setting :
(1)  Set Shadowsockes as global proxy mode;

(2)  Set GIT proxy as following:
git config --global http.proxy http://localhost:1080
git config --global https.proxy https://localhost:1080

(3)  Set Winhttp proxy as following:
c:\>netsh

netsh>winhttp
netsh winhttp>set proxy localhost:58328

(4)  Set the http_proxy, https_proxy environment variables as following:
c:\>set http_proxy=http://localhost:58328
c:\>set https_proxy=https://localhost:58328

在E:\depot_tools下新建http_proxy.boto，内容如下： 
[Boto] 
proxy= 127.0.0.1 
proxy_port= 1080 

set http_proxy=http://127.0.0.1:58328
set https_proxy=http://127.0.0.1:58328
设置下载工具git代理： 
git config --global http.proxy http://127.0.0.1:58328
git config --global https.proxy https://127.0.0.1:58328

取消代理：
  git config --global --unset http.proxy
  git config --global --unset https.proxy
设置BOTO代理，解决download google storage失败问题： 
set NO_AUTH_BOTO_CONFIG=D:\depot_tools\http_proxy.boto 
设置不再次下载工具链： 
set DEPOT_TOOLS_WIN_TOOLCHAIN=0 
设置生成工程环境变量： 
set GYP_GENERATORS=msvs-ninja,ninja 
set GYP_MSVS_VERSION=2015 
首次下载输入下载命令： 
fetch webrtc 
下次更新
gclient sync 

$(WebrtcPath)\src\out\x86Re\lib;

gn gen out/x862015  --ide="vs2015" --args="is_debug=true target_cpu=\"x86\""
gn gen out/x86Re  --ide="vs2015" --args="is_debug=false target_cpu=\"x86\""
gn gen out/x642015Re  --ide="vs2015" --args="is_debug=false target_cpu=\"x64\""
ninja -C out/x862015

ninja -C out/x642015Re
Android：
export GYP_DEFINES="OS=android"
fetch --nohooks webrtc_android
gclient sync

ninja -C out/x86Re
git取消
git config --global --unset http.proxy
git config --global --unset https.proxy

SignalEncoderConfigurationChanged
export PATH="D://depot_tools:${PATH}"
python tools/git-sync-deps