In order to run both the visual studio tools and the binaries built
by them (and ninja), we need to ensure that the VS runtime DLLs
are available in the path.
In the GYP build, we accomplish this by copying them into the
Debug and Debug_x64 dirs as appropriate inside the gyp_chromium
script.
In the pure-GN build, then, things would be broken, so we need to
modify the GN build to do the copy as well, or we need to inject
a step somewhere that happens after GN runs but before Ninja tries
to run (since none of the toolchain binaries will work).
This patch accomplishes this by calling out to vs_toolchain.py to
copy the DLLs as neede when the toolchain is defined. This is somewhat
less than ideal (makes 'gn gen' slower) but seems better than forcing
devs to have to run an additional command.
In addition, the GYP build writes targets into Debug and Debug_x64
concurrently. This doesn't really carry over into GN correctly, and
we probably only ever want to write targets into Debug and Debug/64
(or some such).
However, the way the toolchains are currently implemented, it's not
clear if this really works and the interplay between 32-bit and 64-bit
is weird (we apparently normally "force" 32-bit even if we set cpu_arch
to 64-bit, and require you to specify force_win64). To work around this
and make sure that we copy the right DLLs for the right arch into the
outer Debug/ directory, this patch temporarily disables the cross-arch
part of the build, forcing the host_toolchain to match the target_toolchain.
This likely means that 'cpu_arch="x86"' works (the default), but the 'host'
binaries like image_diff and mksnapshot will be compiled in 32-bit mode,
not 64-bit mode. 'cpu_arch="x64" force_win64=true' should also work, and
produce all-64-bit binaries. 'cpu_arch="x64"' does not work at all and
won't until we can clean up the above stuff.
R=scottmg@chromium.org, brettw@chromium.org
BUG=430661
Review URL: https://codereview.chromium.org/722723004
Cr-Original-Commit-Position: refs/heads/master@{#304310}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 0b95195e49489b7a4d87048d2ce4b747173a5b8a
7265358749