Add ephemeral support to BroadcastChannel

[goodov]

BroadcastChannel currently is not blocked and is shared between 1p and 3p frames with the same origin. We can use ephemeral-specific origins to partition it in ephemeral contexts.

[stephendonner]

Setting QA/Blocked until we get a test plan; mind doing the honors again, @goodov 🙏

[goodov]

Ephemeral/partitioned BroadcastChannel manual test can be done like this:

1. Open https://dev-pages.brave.software/storage/frames.html
2. Open https://dev-pages.brave.software/storage/frames.html in a second tab
3. Open https://dev-pages.bravesoftware.com/storage/frames.html in a third tab
4. Register BroadcastChannel via DevTools in main, nested first-party, nested third-party frames in all tabs with this snippet:
   bc = new BroadcastChannel('bc'); bc.onmessage = (msg) => { console.log(((window.self !== window.parent) ? 'received in iframe: ' : 'received in main frame: ') + window.location.href); console.log(msg); }
5. Send a broadcast message from different frames using this snippet: bc.postMessage('msg')
6. Expect messages are send and received according to the ephemeral rules:
   • All first-party frames share same BroadcastChannel per origin.
   • All third-party frames share same BroadcastChannel, but this channel is separate for each main frame eTLD+1 origin. For example, b.com nested in a.com will have a virtual channel a.com+b.com, but b.com nested in c.com will have a virtual channel c.com+b.com.
   • Third-party frames cannot receive messages from first-party frames of the same origin. Example: b.com nested in a.com cannot receive messages sent from b.com opened in another tab.

Test cases:

1. Send from brave.software main frame, expect received in another brave.software tab and nested first-party brave.software frames, but not in third-party brave.software frames.
2. Send from third-party bravesoftware.com frame inside brave.software, expect received in third-party bravesoftware.com frames inside brave.software.
3. Send from bravesoftware.com main frame, expect received in nested first-party bravesoftware.com frame, but not in third-party bravesoftware.com frames.

[stephendonner]

Verified PASSED using the testplan #17220 (comment) with modifications by me, reviewed by @goodov, on build

Brave	1.29.61 Chromium: 92.0.4515.131 (Official Build) beta (x86_64)
Revision	6b8d6c56ce21e38a72f7c4becb5abc1fa5134f29-refs/branch-heads/4515@{#1933}
OS	macOS Version 12.0 (Build 21A5304g)

PREREQUISITE: follow the testplan steps 1-4, first.

Testcase 1:

1. in tab 1, send the message using bc.postMessage('message') from top/dev-pages.brave.software frame
2. confirm one message shows up in the 1st tab: received in iframe
3. confirm two messages shows up in the 2nd tab: received in mainframe, received in iframe
4. ensure no messages received in the 3rd tab

steps 1-2	step 3	step 4

Testcase 2:

1. from tab 1, send message using bc.postMessage('message') from storage.html/dev-pages.bravesoftware.com frame
2. confirm message was received in tab 2: received in iframe <...> dev-pages.bravesoftware.com
3. ensure no messages received in the 3rd tab

steps 1-2	step 2	step 3

Testcase 3:

1. from tab 3, send message using bc.postMessage('message') from top/dev-pages.bravesoftware.com frame
2. confirm one message shows up in the 3rd tab: received in iframe
3. a) confirm message was not received in tab 1 and b) tab 2

step 1	step 2	step 3a	step 3b

---

Verified PASSED using the testplan #17220 (comment)

Brave	1.29.68 Chromium: 92.0.4515.159 (Official Build) beta (64-bit)
Revision	0185b8a19c88c5dfd3e6c0da6686d799e9bc3b52-refs/branch-heads/4515@{#2052}
OS	Linux

PREREQUISITE: follow the testplan steps 1-4, first.

Testcase 1:

1. in tab 1, send the message using bc.postMessage('message') from top/dev-pages.brave.software frame
2. confirm one message shows up in the 1st tab: received in iframe
3. confirm two messages shows up in the 2nd tab: received in mainframe, received in iframe
4. ensure no messages received in the 3rd tab

step 1	step 2	steps 3-4

Testcase 2:

1. from tab 1, send message using bc.postMessage('message') from storage.html/dev-pages.bravesoftware.com frame
2. confirm message was received in tab 2: received in iframe <...> dev-pages.bravesoftware.com
3. ensure no messages received in the 3rd tab

step 1	step 2	step 3

Testcase 3:

1. from tab 3, send message using bc.postMessage('message') from top/dev-pages.bravesoftware.com frame
2. confirm one message shows up in the 3rd tab: received in iframe
3. a) confirm message was not received in tab 1 and b) tab 2

steps 1-2	step 3a	step 3b

---

Verification passed on

Brave | 1.29.75 Chromium: 93.0.4577.58 (Official Build) (64-bit)
-- | --
Revision | c4410ece044414ea42fa4ba328d08195e818a99c-refs/branch-heads/4577@{#1076}
OS | Windows 10 OS Version 2009 (Build 19043.1165)

Verified the test plan from #17220 (comment)

Testcase 1:

1. in tab 1, send the message using bc.postMessage('message') from top/dev-pages.brave.software frame
2. confirm one message shows up in the 1st tab: received in iframe
3. confirm two messages shows up in the 2nd tab: received in mainframe, received in iframe
4. ensure no messages received in the 3rd tab

steps 1-2	step 3	step 4

Testcase 2:

1. from tab 1, send message using bc.postMessage('message') from storage.html/dev-pages.bravesoftware.com frame
2. confirm message was received in tab 2: received in iframe <...> dev-pages.bravesoftware.com
3. ensure no messages received in the 3rd tab

steps 1-2	step 2	step 3

Testcase 3:

1. from tab 3, send message using bc.postMessage('message') from top/dev-pages.bravesoftware.com frame
2. confirm one message shows up in the 3rd tab: received in iframe
3. a) confirm message was not received in tab 1 and b) tab 2

step 2	step 3a	step 3b

[srirambv]

Verification passed on Oppo Reno 5 with Android 11 running 1.29.68 xs64 Beta build

• Verified steps from Add ephemeral support to BroadcastChannel #17220 (comment)

Scenario 1:

• Set broadcast message on all 3 frames for all 3 tabs
• Set tab 1 to top main frame
• Send broadcast message from tab 1
• Tab 2 receives two broad case message, one from top frame and one from iframe
• Tab 1 only see's iframe broadcast message
• Tab 3 doesn't get any broadcast message

Scenario 2:

• Set broadcast message on all 3 frames for all 3 tabs
• Set tab 1 to first nested frame
• Send broadcast message from tab 1
• Tab 2 receives one broadcast message
• Tab 3 doesn't receive any broadcast message

Scenario 3:

• Set broadcast message on all 3 frames for all 3 tabs
• Set tab 3 to top main frame
• Send a broadcast message from tab 3
• Only tab 3 gets a single response, other 2 tabs doesn't get any broadcast message

---

Verification passed on Samsung Tab A with Android 11 running 1.29.68 xs64 Beta build

• Verified steps from Add ephemeral support to BroadcastChannel #17220 (comment)

Scenario 1:

• Set broadcast message on all 3 frames for all 3 tabs
• Set tab 1 to top main frame
• Send broadcast message from tab 1
• Tab 2 receives two broad case message, one from top frame and one from iframe
• Tab 1 only see's iframe broadcast message
• Tab 3 doesn't get any broadcast message
  

Scenario 2:

• Set broadcast message on all 3 frames for all 3 tabs
• Set tab 1 to first nested frame
• Send broadcast message from tab 1
• Tab 2 receives one broadcast message
• Tab 3 doesn't receive any broadcast message
  

Scenario 3:

• Set broadcast message on all 3 frames for all 3 tabs
• Set tab 3 to top main frame
• Send a broadcast message from tab 3
• Only tab 3 gets a single response, other 2 tabs doesn't get any broadcast message