Proposal: unique frameIds across windows and tabs

[carlosjeurissen]

Background

1. Proposed in request: allow to retrieve a frameID from an <iframe> element #12, is the ability to be able to get a frameId based on the windowObject of a frame. See also: Publish minutes of 2021-09-30 meeting #89
2. Proposed in Proposal: Provide a secure drop-in replacement for window.postMessage() #77 (comment), is the ability to send messages to frames as alternative to window.postMessage which has many potential security issues.
3. Proposed in Proposal: scripting.executeScript without specifying tabId #91, is the ability to run executeScript and insertCSS with just specifying the frameId without specifying the tabId. As the tabId might not always be available.

Proposal

The above three proposals all very much rely on frameIds to be unique across windows and tabs. Making them uniquely identifiable. This seems to already be the case in some browsers. Seems Firefox and Chromium have unique frameIds. Yet it's very welcome to have this confirmed for all browsers, Firefox, Chromium, Edge, Safari, Naver Whale and others.

[carlosjeurissen]

As mentioned in the past by Google, we can consider making the frameId a random integer for security reasons. See:
#12 (comment)

In addition, I was wondering if there is a specific reason why the main_frame is always 0? If we let it be part of the unique frameIds this would also help with the mentioned proposals.