Better support for Linux ARM machines

[zcbenz]

This issue lists the tasks on making Electron support more ARM machines.

• Enable building libchromiumcontent locally with Electron together

http://electron.atom.io/docs/development/build-instructions-linux/#advanced-topics

• Make it possible to pass ARM related configurations when building

$ ./script/bootstrap.py -v --build_libchromiumcontent \
                           --target_arch=arm \
                           --defines='arm_version=7 arm_float_abi=softfp'

• Add docs on which ARM related configurations we can provide
• Add support for ARM 64

$ ./script/bootstrap.py -v --build_libchromiumcontent \
                           --target_arch=arm64

• Provide prebuilt builds for popular ARM machines

Related: #2343

• Enable building without using sysroot

$ ./script/bootstrap.py -v --build_libchromiumcontent \
                           --target_arch=arm
                           --disable_sysroot

• Enable building with GCC provided by user

$ export CC=my-weird-gcc
$ export CXX=my-werid-g++
$ export CPPFLAGS=--my-weird-flags
$ ./script/bootstrap.py -v --build_libchromiumcontent \
                           --disable_clang
                           --target_arch=arm

Feel free to share opinions here if anyone thinks this is not enough for building Electron for your ARM machine.

/cc @iolsen @francoislaberge

[dantwinkler]

FYI, it looks like support for arm64 was merged in: 1257dee

Electron for arm64 builds successfully now that libchromiumcontent merged the arm64 support. Will this be included in future official builds for electron?

[zeke]

@groundwater is giving it a shot here: electron/libchromiumcontent#334

[groundwater]

We have a PR here #10205 for Linux.

[galvesribeiro]

Any updates on getting this out?

[zcbenz]

This issue was mostly about libchromiumcontent which had already been removed, so I'm closing it. Please create new issues if there is any problem with arm Linux support.