About the ‘use_browser_spellchecker’ and ‘use_renderer_spellchecker’ build time flag.

use_browser_spellchecker

Use the operating system‘s spellchecker rather than hunspell. This does not affect the “red underline” spellchecker which can consult Google’s server-based spellcheck service.

use_renderer_spellchecker

Use hunspell spellchecker rather than the operating system's spellchecker.

Note:

For most operating system except Windows, the decision to use the platform spellchecker or hunspell spellchecker is made at build time. Therefore, use_browser_spellchecker and use_renderer_spellchecker are mutually exclusive for most operating systems except Windows.

For Windows OS, the decision to use the platform spellchecker or hunspell spellchecker is made during runtime. Therefore, we include both build flags if the platform is Windows.

We also need to create the runtime feature flag kWinUseBrowserSpellChecker for Windows OS. The feature flag is used to choose between the platform or hunspell spellchecker at runtime.