Add interface definitions for Chromium

[dotproto]

This pull request introduces an initial set of WebExtensions definitions for the Chromium project. Additional details on how the data was gathered can be found in interfaces/chromium/README.md.

[Rob--W]

This patch includes files that are specific to legacy Chrome Apps, as well as private APIs.

The Chrome Apps APIs can certainly be omitted, as they (chrome/common/apps/) cannot be used in any extension.

If we do that, then we can reduce the number of results from 203 to:

• Chromium code search: (file:^chrome/common/extensions/api/ OR file:^extensions/common/api/) (file:.json$ OR file:.idl)
  • 198 results
  • URL: https://source.chromium.org/search?q=(file:%5Echrome%2Fcommon%2Fextensions%2Fapi%2F%20OR%20file:%5Eextensions%2Fcommon%2Fapi%2F)%20(file:.json$%20OR%20file:.idl)&sq=&ss=chromium

If I omit private and clear internal implementation details, then we have:

• Chromium code search: (file:^chrome/common/extensions/api/ OR file:^extensions/common/api/) (file:.json$ OR file:.idl) -file:_private -file:_internal
  • 132 results
  • URL: https://source.chromium.org/search?q=(file:%5Echrome%2Fcommon%2Fextensions%2Fapi%2F%20OR%20file:%5Eextensions%2Fcommon%2Fapi%2F)%20(file:.json$%20OR%20file:.idl)%20-file:_private%20-file:_internal&ss=chromium

There are still many non-public APIs. If you'd like to be extra precise, you could look at entries with "extension_types" containing "extension" WITHOUT "whitelist" at chrome/common/extensions/api/_permission_features.json and extensions/common/api/_permission_features.json. This will give a list of public APIs (filter by "channel": "stable" to only get stable APIs, but for the purpose of this spec we probably accept pre-release API definitions too). Next, filter by APIs that depend on non-public permissions (listed at chrome/common/extensions/api/_api_features.jso and extensions/common/api/_api_features.json).

[mukul-p]

There is a mix of idl and json files. This is a good start, but i feel that having a common format (for one platform) would be consistent. Comments?

[dotproto]

There is a mix of idl and json files. This is a good start, but i feel that having a common format (for one platform) would be consistent. Comments?

IMO that would be ideal, but for better or worse Chromium currently uses a mix of formats. Normalizing them here is out of scope. This PR only aims to provide a snapshot of Chromium's interface definitions and provide guidance on how to manually update them in the future.