[M125][compose] Handles keyboard navigation with the new submenu.

Key handling added:

1. Horizontal arrows are used to open/close the subpopup.
2. Shift+TAB on an open subpopup closes it and focuses on the parent
   content area.
3. On a subpopup, vertical arrows are used to select different child
   suggestions available.

Demo: https://screencast.googleplex.com/cast/NDc4NzI0ODEzNzUwMjcyMHw5N2M1YjA2YS04Mg
Bug: b/333929225
Change-Id: Ie6c4cbc980ad7c57cf0e8f9bd2447df5751ea922
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5513776
Cr-Original-Commit-Position: refs/heads/main@{#1296747}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5519285
Commit-Queue: Trevor Perrier <perrier@chromium.org>
Reviewed-by: Bruno Braga <brunobraga@google.com>
Reviewed-by: Justin DeWitt <dewittj@chromium.org>
Cr-Commit-Position: refs/branch-heads/6422@{#787}
Cr-Branched-From: 9012208d0ce02e0cf0adb9b62558627c356f3278-refs/heads/main@{#1287751}
3 files changed
tree: 667dc2b5699bd4cdb5c9b159f0339c57e6b96b74
  1. android_webview/
  2. apps/
  3. ash/
  4. base/
  5. build/
  6. build_overrides/
  7. buildtools/
  8. cc/
  9. chrome/
  10. chromecast/
  11. chromeos/
  12. codelabs/
  13. components/
  14. content/
  15. courgette/
  16. crypto/
  17. dbus/
  18. device/
  19. docs/
  20. extensions/
  21. fuchsia_web/
  22. gin/
  23. google_apis/
  24. google_update/
  25. gpu/
  26. headless/
  27. infra/
  28. ios/
  29. ipc/
  30. media/
  31. mojo/
  32. native_client_sdk/
  33. net/
  34. pdf/
  35. ppapi/
  36. printing/
  37. remoting/
  38. rlz/
  39. sandbox/
  40. services/
  41. skia/
  42. sql/
  43. storage/
  44. styleguide/
  45. testing/
  46. third_party/
  47. tools/
  48. ui/
  49. url/
  50. webkit/
  51. .clang-format
  52. .clang-tidy
  53. .clangd
  54. .eslintrc.js
  55. .git-blame-ignore-revs
  56. .gitallowed
  57. .gitattributes
  58. .gitignore
  59. .gitmodules
  60. .gn
  61. .mailmap
  62. .rustfmt.toml
  63. .vpython3
  64. .yapfignore
  65. ATL_OWNERS
  66. AUTHORS
  67. BUILD.gn
  68. CODE_OF_CONDUCT.md
  69. codereview.settings
  70. CPPLINT.cfg
  71. DEPS
  72. DIR_METADATA
  73. LICENSE
  74. LICENSE.chromium_os
  75. OWNERS
  76. PRESUBMIT.py
  77. PRESUBMIT_test.py
  78. PRESUBMIT_test_mocks.py
  79. README.md
  80. WATCHLISTS
README.md

Logo Chromium

Chromium is an open-source browser project that aims to build a safer, faster, and more stable way for all users to experience the web.

The project's web site is https://www.chromium.org.

To check out the source code locally, don't use git clone! Instead, follow the instructions on how to get the code.

Documentation in the source is rooted in docs/README.md.

Learn how to Get Around the Chromium Source Code Directory Structure.

For historical reasons, there are some small top level directories. Now the guidance is that new top level directories are for product (e.g. Chrome, Android WebView, Ash). Even if these products have multiple executables, the code should be in subdirectories of the product.

If you found a bug, please file it at https://crbug.com/new.