system_api: Public InputNodeGainChanged for dbus api

InputNodeGainChanged indicate the current gain for the node

BUG=b:255278344
TEST=cros-workon-${BOARD} start chromeos-base/system_api
TEST=FEATURES=test emerge-${BOARD} chromeos-base/system_api

Cq-Depend: chromium:4125095
Change-Id: I9f1121996d3addf674ca197741a487eeb560235d
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform2/+/4125078
Reviewed-by: Chih-Yang Hsia <paulhsia@chromium.org>
Reviewed-by: Yu-Hsuan Hsu <yuhsuan@chromium.org>
Commit-Queue: Baili Deng <bailideng@google.com>
Tested-by: Baili Deng <bailideng@google.com>
NOKEYCHECK=True
GitOrigin-RevId: b764b9d29ed2420194badca532c4e0feded2b334
1 file changed
tree: aeabce6b734a90b432fb148926853fd1b746cd85
  1. constants/
  2. dbus/
  3. mojo/
  4. src/
  5. switches/
  6. .gitignore
  7. BUILD.gn
  8. build.rs
  9. Cargo.toml
  10. DIR_METADATA
  11. LICENSE
  12. OWNERS
  13. README.md
  14. system_api.pc
README.md

This directory (platform2/system_api) contains constants and definitions like D-Bus service names that are shared between Chromium and Chromium OS.

This directory is only for things like headers and .proto files. No implementation should be added.

When writting a .proto file make sure to use:

option optimize_for = LITE_RUNTIME;

This will force usage of a lite protobuf instead of a full/heavy weight protobuf. The browser only links against the light version, so you will get cryptic link errors about missing parts of Message if you define a protobuf here and then try to use it in Chrome. Currently CrOS links against the full protobuffer library, but that might change in the future.

When declaring a protobuf, avoid use of required unless it is exactly what you mean. "Required is Forever" and very rarely should actually be used. Consult Protocol Buffer Basics: C++ for a detailed of this issue.