Add angle_root in build_overrides/angle.gni

This patch defines 'angle_root' in //build_overrides/angle.gni so that
the hard-coded assignment of 'angle_root' in the GN file of ANGLE
(//third_party/angle/gni/angle.gni) can be removed in the following CL:
https://chromium-review.googlesource.com/c/angle/angle/+/1522912

Bug: angleproject:3263
Change-Id: Ifc35dcc7782f84ebc1b9fb53f8f77c468bddc80a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1663737
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Jiawei Shao <jiawei.shao@intel.com>
Cr-Original-Commit-Position: refs/heads/master@{#670048}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: ea6a9a26eb6f0167635eece025a61338a4861c74
1 file changed
tree: 451358127780352131dc13ded005b1be4124102b
  1. OWNERS
  2. README.md
  3. angle.gni
  4. build.gni
  5. dawn.gni
  6. glslang.gni
  7. gtest.gni
  8. pdfium.gni
  9. shaderc.gni
  10. spirv_tools.gni
  11. vulkan_common.gni
  12. vulkan_loader.gni
  13. vulkan_tools.gni
  14. vulkan_validation_layers.gni
README.md

Build overrides in GN

This directory is used to allow different products to customize settings for repos that are DEPS'ed in or shared.

For example: V8 could be built on its own (in a “standalone” configuration), and it could be built as part of Chromium. V8 might define a top-level target, //v8:d8 (a simple executable), that should only be built in the standalone configuration. To figure out whether or not it should be in a standalone configuration, v8 can create a file, build_overrides/v8.gni, that contains a variable, build_standalone_d8 = true. and import it (as import(“//build_overrides/v8.gni”) from its top-level BUILD.gn file.

Chromium, on the other hand, might not need to build d8, and so it would create its own build_overrides/v8.gni file, and in it set build_standalone_d8 = false.

The two files should define the same set of variables, but the values can vary as appropriate to the needs of the two different builds.

The build.gni file provides a way for projects to override defaults for variables used in //build itself (which we want to be shareable between projects).

TODO(crbug.com/588513): Ideally //build_overrides and, in particular, //build_overrides/build.gni should go away completely in favor of some mechanism that can re-use other required files like //.gn, so that we don't have to keep requiring projects to create a bunch of different files to use GN.