背景：
在cef上进行二次开发，发现默认不只支持h264解码。需要重新编译chromium解决。
步骤：
https://bitbucket.org/chromiumembedded/cef/wiki/MasterBuildQuickStart.md#markdown-header-linux-setup 为官方编译指导。主要步骤已经十分详细。下面红字部分补充一些实际编译遇到的问题。
前提：
需要好用的vpn，或者ssr 加 proxifier 实现全局代理。
Linux Setup
What's Required
Ubuntu 16.04 LTS 64-bit is recommended. Building with other versions or distros has not been tested and may experience issues.
At least 6GB of RAM and 40GB of free disk space.(内存实在不够，可以用swap凑，4g还是起码要的，否则极度影响编译速度。 硬盘空间最好60g以上，40g可能不够)
Approximately 2 hours with a fast internet connection (25Mbps) and fast build machine (2.6Ghz+, 4+ logical cores).（虚拟机，单核也没问题，就是耗时巨长。。）
Step-by-step Guide
In this example "~" is "/home/marshall". Note that in some cases the absolute path must be used. Environment variables described in this section can be added to your "~/.profile" or "~/.bashrc" file to persist them across sessions.
整体主要是用户和权限问题，需要非root用户执行
1. Create the following directories.
mkdir ~/code
mkdir ~/code/automate
mkdir ~/code/chromium_git
2. Download and run "~/code/install-build-deps.sh" to install build dependencies. Answer Y (yes) to all of the questions.
cd ~/code
sudo apt-get install curl
curl 'https://chromium.googlesource.com/chromium/src/+/master/build/install-build-deps.sh?format=TEXT' | base64 -d > install-build-deps.sh
chmod 755 install-build-deps.sh
sudo ./install-build-deps.sh --no-arm --no-chromeos-fonts --no-nacl
3. Install the "libgtkglext1-dev" package required by the cefclient sample application.
sudo apt-get install libgtkglext1-dev
4. Download "~/code/depot_tools" using Git.
cd ~/code
git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git
5. Add the "~/code/depot_tools" directory to your PATH. Note the use of an absolute path here.
export PATH=/home/marshall/code/depot_tools:$PATH
6. Download the "~/automate/automate-git.py" script.
cd ~/code/automate
wget https://bitbucket.org/chromiumembedded/cef/raw/master/tools/automate/automate-git.py
7. Create the "~/code/chromium_git/update.sh" script with the following contents.
（环境变量主要是为了加入对h264解码的支持，chromium默认是不支持h264的）
#!/bin/bash
export DEPOT_TOOLS_UPDATE=0
export CEF_USE_GN=1
export GN_DEFINES="is_official_build=true proprietary_codecs=true ffmpeg_branding=Chrome"
export GYP_DEFINES=buildtype=Official
python ../automate/automate-git.py --download-dir=/home/marshall/code/chromium_git --depot-tools-dir=/home/marshall/code/depot_tools --no-distrib --no-build
(--branch=3683 指定对应要下载的分支版本 --force-clean 最好加上，可以去除残留)
Give it executable permissions.
cd ~/code/chromium_git
chmod 755 update.sh
Run the "update.sh" script and wait for CEF and Chromium source code to download. CEF source code will be downloaded to "~/code/chromium_git/cef" and Chromium source code will be downloaded to "~/code/chromium_git/chromium/src". After download completion the CEF source code will be copied to "~/code/chromium_git/chromium/src/cef".
cd ~/code/chromium_git
./update.sh
8. Create the "~/code/chromium_git/chromium/src/cef/create.sh" script with the following contents.】
（环境变量主要是为了加入对h264解码的支持，chromium默认是不支持h264的）
#!/bin/bash
export DEPOT_TOOLS_UPDATE=0
export CEF_USE_GN=1
export GN_DEFINES="is_official_build=true proprietary_codecs=true ffmpeg_branding=Chrome use_jumbo_build=true"
export GYP_DEFINES=buildtype=Official
export GN_DEFINES=use_jumbo_build=true
./cef_create_projects.sh
Give it executable permissions.
cd ~/code/chromium_git/chromium/src/cef
chmod 755 create.sh
Run the "create.sh" script to create Ninja project files. Repeat this step if you change the project configuration or add/remove files in the GN configuration (BUILD.gn file).
cd ~/code/chromium_git/chromium/src/cef
./create.sh
9. Create a Debug build of CEF/Chromium using Ninja. Edit the CEF source code at "~/code/chromium_git/chromium/src/cef" and repeat this step multiple times to perform incremental builds while developing. Note the additional "chrome_sandbox" target required by step 10.
cd ~/code/chromium_git/chromium/src
ninja -C out/Debug_GN_x64 cef chrome_sandbox
10. Set up the Linux SUID sandbox.
# This environment variable should be set at all times.
export CHROME_DEVEL_SANDBOX=/usr/local/sbin/chrome-devel-sandbox
# This command only needs to be run a single time.
cd ~/code/chromium_git/chromium/src
sudo BUILDTYPE=Debug_GN_x64 ./build/update-linux-sandbox.sh
11. Run the cefclient sample application.
cd ~/code/chromium_git/chromium/src
./out/Debug_GN_x64/cefclient
相关问题：
1、________ running 'cipd ensure -log-level error -root /home/z/code/chromium_git/chromium -ensure-file /tmp/tmpkunrfR.ensure' in '.'
CIPD selfupdate failed. Trying to bootstrap the CIPD client from scratch...
[P21376 19:08:21.295 client.go:309 W] RPC failed transiently. Will retry in 1s {"error":"failed to send request: Post https://chrome-infra-packages.appspot.com/prpc/cipd.Repository/ResolveVersion: proxyconnect tcp: net/http: TLS handshake timeout", "host":"chrome-infra-packages.appspot.com", "method":"ResolveVersion", "service":"cipd.Repository", "sleepTime":"1s"
解决：查看代理设置 默认https是优先选择的，如果https不可用，直接设置为export https_proxy=http://
2、FAILED: gen/mojo/public/js/mojo_bindings_lite.js
解决：安装jdk
3、clang++: error: unable to execute command: Killed
clang++: error: clang frontend command failed due to signal (use -v to see invocation)
clang version 9.0.0 (trunk 351477)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: ../../third_party/llvm-build/Release+Asserts/bin
clang++: note: diagnostic msg: PLEASE submit a bug report to https://bugs.llvm.org/ and include the crash backtrace, preprocessed source, and associated run script.
clang++: note: diagnostic msg:
解决：内存不够，增加swap空间
sudo fallocate -l 6G /swapfile
sudo chmod 600 /swapfile
sudo mkswap /swapfile
sudo swapon /swapfile
开机自动挂载swap：
使用 vi 或 nano 在 /etc/fstab 文件底部添加如下内容：
/swapfile none swap sw 0 0
4、WARNING: subprocess '"git" "-c" "core.deltaBaseCacheLimit=2g" "fetch" "origin"' in
解决：
在对应目录执行 git remote prune origin（同步远程仓库）