[base] FlatHashMap: don't invalidate pointer if key exists

Before this CL the insertion code caused both:
 - Insert(already_existing_key, ...)
 - operator[](already_existing_key)
To rehash, and hence invalidate pointers, even in the case of
the key already existing. This is because the load-factor check
was performed in the Insert() prologue, before even checking if
the key did exist already.
This CL also gets rid of the |size_plus_tombstones_| and makes
the load check just based on the |size_|. The extra layer of
complexity didn't bring any meaningful benefit.

Test: FlatHashMapTest.DontRehashIfKeyAlreadyExists
Bug: crbug.com/1272018
Bug: 207393956
Change-Id: I9d7c6a7a86fd16656fd6c41a5778fb7705b2418e
2 files changed
tree: dac02f8eba18773e1d0f69e232397079e8be7ef8
  1. .github/
  2. bazel/
  3. build_overrides/
  4. buildtools/
  5. debian/
  6. docs/
  7. examples/
  8. gn/
  9. include/
  10. infra/
  11. protos/
  12. src/
  13. test/
  14. tools/
  15. ui/
  16. .clang-format
  17. .clang-tidy
  18. .gitattributes
  19. .gitignore
  20. .gn
  21. .style.yapf
  22. Android.bp
  23. Android.bp.extras
  24. BUILD
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  26. BUILD.gn
  27. CHANGELOG
  28. codereview.settings
  29. DIR_METADATA
  30. heapprofd.rc
  31. LICENSE
  32. meson.build
  33. METADATA
  34. MODULE_LICENSE_APACHE2
  35. OWNERS
  36. perfetto.rc
  37. PerfettoIntegrationTests.xml
  38. PRESUBMIT.py
  39. README.chromium
  40. README.md
  41. TEST_MAPPING
  42. traced_perf.rc
  43. 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.