Native Client is a deprecated sandboxing technology. It is currently used by a few third party chrome extensions and chrome apps. Many of the original project pages are not longer available. Some documentation can be found at:
The following list describes major files and directories that you‘ll see in your working copy of the repository, including some directories that don’t exist until you've built Native Client. Paths are relative to the native_client directory.
COPYING NOTICE README.md RELEASE_NOTES documentation/: Documentation, release, and license information.
SConstruct scons.bat scons scons-out/ site_scons/: Build-related files. The scons.bat and scons files, with data from SConstruct, let you build Native Client and its tests. The scons-out and site-scons directories don‘t exist in the git repository; they’re created when Native Client is built. The scons-out/*/staging directories contain files, such as the Native Client plug-in and compiled examples, that let you use and test Native Client.
src/: Core source code for Native Client.
src/include/: Header files that are missing from some platforms and are used by more than one major part of Native Client
src/shared/: Source code that's used by both trusted code (such as the service runtime) and untrusted code (such as Native Client modules)
src/third_party: Other people's source code
src/trusted/: Source code that's used only by trusted code
src/untrusted/: Source code that's used only by untrusted code
tests/common/: Source code for examples and tests.
../third_party/: Third-party source code and binaries that aren't part of the service runtime. When built, the Native Client toolchain is in src/third_party/nacl_sdk/.
tools/: Utilities such as the plug-in installer.