882b7bf236
Declare the pdf_enable_rust_bmp build argument, its override pdf_enable_rust_bmp_override, and define the PDF_ENABLE_RUST_BMP preprocessor macro when pdf_use_skia && pdf_enable_rust_bmp is active. This allows external build recipes to configure the GN argument prior to activating the Rust-based BMP decoder in a follow-up change. TAG=agy CONV=f457c92a-036e-44c5-89eb-1caaf0d672f5 Bug: 537855738 Change-Id: Ia44c2b798b5c26cac89a8025b83d8244e1978655 Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/152810 Reviewed-by: Tom Sepez <tsepez@chromium.org> Commit-Queue: Tom Sepez <tsepez@chromium.org> Reviewed-by: Lei Zhang <thestig@chromium.org>
Build overrides in GN
This directory is used to allow different products to customize settings for repos which are DEPS'ed in or shared.
For example: V8 can be built on its own (in a "standalone" configuration),
and it can be built as part of Chromium. V8 defines a top-level
target, //v8:d8 (a simple executable), which will only be built in the
standalone configuration. To indiate itis a standalone configuration, v8 can
create a file, build_overrides/v8.gni, containing 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, does 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 may vary as appropriate to suit 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 will 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.