GN: support cross-compilation with same cpu and os

Before this CL we use two distinct toolchains only when
target_os != host_os or target_cpu != host_cpu.
This isn't enough for CrOS where both the host and target are x64
(x86_64 really), but they need different toolchain arguments.
This CL further conditions the is_cross_comping logic looking at
target_triplet.
In order to do so, the default initialization of target_triplet
is moved to BUILDCONFIG.gn (which is the one in charge of
setting is_cross_compiling) and the existing logic is moved
to _target_triplet (with underscore).

Bug: 147789115
Change-Id: I5c239e9cb35c0c5779ef8c615eaa9de309637544
3 files changed
tree: 11a4fb7df4505ef969ab51bb525fd429f3b92c70
  1. bazel/
  2. build_overrides/
  3. buildtools/
  4. debian/
  5. docs/
  6. examples/
  7. gn/
  8. include/
  9. infra/
  10. protos/
  11. src/
  12. test/
  13. tools/
  14. ui/
  15. .clang-format
  16. .clang-tidy
  17. .gitignore
  18. .gn
  19. .style.yapf
  20. Android.bp
  21. Android.bp.extras
  22. BUILD
  23. BUILD.extras
  24. BUILD.gn
  25. CHANGELOG
  26. codereview.settings
  27. heapprofd.rc
  28. LICENSE
  29. METADATA
  30. MODULE_LICENSE_APACHE2
  31. OWNERS
  32. perfetto.rc
  33. PRESUBMIT.py
  34. README.chromium
  35. README.md
  36. TEST_MAPPING
  37. traced_perf.rc
  38. WORKSPACE
README.md

Perfetto - System profiling, app tracing and trace analysis

Perfetto is a production-grade open-source stack for performance instrumentation and trace analysis. It offers services and libraries and for recording system-level and app-level traces, native + java heap profiling, a library for analyzing traces using SQL and a web-based UI to visualize and explore multi-GB traces.

See https://perfetto.dev/docs or the /docs/ directory for documentation.