Add window.h5vcc.accessibility

[haozheng-cobalt]

This PR adds window.h5vcc.accessibility APIs.
There are 2 exposed attributes textToSpeech which is readonly, and ontexttospeechchange which would trigger register callback only from C++ backend when a11y settings are changed.

b/391708407

[andrewsavage1]

Does this correspond to a c25 web api? The name is not very similar to a c25 one, so it's unclear.

[haozheng-cobalt]

No, this does not match C25 web API exactly. I'm following the blink syntax standard for creating EventHandler, I think our other new h5vcc web APIs are following this syntax too, e.g. in h5vcc_metrics.idl and h5vcc_runtime.idl

[johnxwork]

You might want to keep the old name for now, otherwise you will need to make a custom Kabuki change and use a loader to test screen reader. Because Kabuki won't recognize this new event.

[andrewsavage1]

Our other h5vcc APIs that used events instead of callbacks change the names of web APIs but all correspond to c25 APIs and so have very similar names to them. If this is a similar case, it should change the name as you did but be similar to the c25 name. Or, if you think the name is inaccurate now that we use events (i.e. if it's addTextToSpeechListener), you should explicitly call out in the comment what this API corresponds to from c25.

[andrewsavage1]

Additionally, you added the API in the IDL but you did not add an implementation for it (even a stub) in the source as far as I can tell

[haozheng-cobalt]

I believe the API will be auto-generated by DEFINE_ATTRIBUTE_EVENT_LISTENER. If not, I'll add to this in follow-up CLs.

[haozheng-cobalt]

Added comments to explain how to map the APIs to C25.

[hlwarriner]

Can you please do the following before merging?

1. Run cobalt just to make sure it doesn't crash on startup.
2. Build the following targets using the new linux-x64x11-no-starboard platform:

$ cobalt/build/gn.py -p linux-x64x11-no-starboard -C devel
$ autoninja -C out/linux-x64x11-no-starboard_devel blink_wpt_tests dump_syms minidump_stackwalk content_shell

This build config uses some strict compiler flags in blink that aren't used for existing CI builds. So it would be good to manually verify the build works until b/405988705 is fixed.

[hlwarriner]

Left a few small comments but otherwise looks good!

[haozheng-cobalt]

Can you please do the following before merging?

1. Run cobalt just to make sure it doesn't crash on startup.
2. Build the following targets using the new linux-x64x11-no-starboard platform:

$ cobalt/build/gn.py -p linux-x64x11-no-starboard -C devel
$ autoninja -C out/linux-x64x11-no-starboard_devel blink_wpt_tests dump_syms minidump_stackwalk content_shell

This build config uses some strict compiler flags in blink that aren't used for existing CI builds. So it would be good to manually verify the build works until b/405988705 is fixed.

You are right!
the linux build does capture a few issues normal ATV build doesn't.
including below that I have addressed:

../../third_party/blink/renderer/modules/cobalt/h_5_vcc.cc:42:7: error: field 'accessibility_' will be initialized after field 'crash_log_' [-Werror,-Wreorder-ctor]

../../third_party/blink/renderer/modules/cobalt/h5vcc_accessibility/h_5_vcc_accessibility.cc:42:1: error: [blink-gc] Base class 'EventTargetWithInlineData' of derived class 'H5vccAccessibility' requires tracing.
void H5vccAccessibility::Trace(Visitor* visitor) const {
^
../../third_party/blink/renderer/modules/cobalt/h5vcc_accessibility/h_5_vcc_accessibility.cc:42:1: error: [blink-gc] Base class 'ExecutionContextLifecycleObserver' of derived class 'H5vccAccessibility' requires tracing.
2 errors generated.

[johnxwork]

You might want to keep the old name for now, otherwise you will need to make a custom Kabuki change and use a loader to test screen reader. Because Kabuki won't recognize this new event.

[hlwarriner]

Can you please do the following before merging?

1. Run cobalt just to make sure it doesn't crash on startup.
2. Build the following targets using the new linux-x64x11-no-starboard platform:

$ cobalt/build/gn.py -p linux-x64x11-no-starboard -C devel
$ autoninja -C out/linux-x64x11-no-starboard_devel blink_wpt_tests dump_syms minidump_stackwalk content_shell

This build config uses some strict compiler flags in blink that aren't used for existing CI builds. So it would be good to manually verify the build works until b/405988705 is fixed.

You are right! the linux build does capture a few issues normal ATV build doesn't. including below that I have addressed:

../../third_party/blink/renderer/modules/cobalt/h_5_vcc.cc:42:7: error: field 'accessibility_' will be initialized after field 'crash_log_' [-Werror,-Wreorder-ctor]

../../third_party/blink/renderer/modules/cobalt/h5vcc_accessibility/h_5_vcc_accessibility.cc:42:1: error: [blink-gc] Base class 'EventTargetWithInlineData' of derived class 'H5vccAccessibility' requires tracing.
void H5vccAccessibility::Trace(Visitor* visitor) const {
^
../../third_party/blink/renderer/modules/cobalt/h5vcc_accessibility/h_5_vcc_accessibility.cc:42:1: error: [blink-gc] Base class 'ExecutionContextLifecycleObserver' of derived class 'H5vccAccessibility' requires tracing.
2 errors generated.

Yup - thanks for fixing them!

[hlwarriner]

If there are different implementations for 1P-ATV and 3P then I'd recommend, instead of branching here on preprocessor conditionals, providing different Mojo implementations.

See the CrashAnnotator Mojo interface as an example:

• ATV impl: https://github.com/youtube/cobalt/blob/main/cobalt/android/apk/app/src/main/java/dev/cobalt/browser/crashannotator/CrashAnnotatorImplFirstParty.java
• 3P impl: https://github.com/youtube/cobalt/blob/main/cobalt/browser/crash_annotator/crash_annotator_impl.h

[haozheng-cobalt]

Thanks Holden, I'll focus on ATV implementation first, in next PR.