Ephemeral storage should work when third-party cookies are blocked

[mrobinson]

Currently ephemeral storage is only used when third-party cookies are unblocked. This ticket addresses changing that behavior so that ephemeral storage is only used when:

1. The ephemeral storage configuration flag is turned on.
2. Ephemeral storage knows how to ephemerally store a particular type of storage.
3. That storage is used in a third-party iframe.
4. That storage would otherwise be blocked by storage settings (either through brave shield or via chromium content settings).

If any of these conditions is not true, ephemeral storage should not be used. If they are all true then storage should be allowed (unblocked) and the data stored should be given an ephemeral lifetime and be partitioned from non-ephemeral storage.

[bridiver]

QA test page https://dev-pages.brave.software/storage/ephemeral-storage.html

[stephendonner]

Verified FIXED using

Brave	1.21.51 Chromium: 88.0.4324.152 (Official Build) beta (x86_64)
Revision	6579930fc53b4dc589c042bec9d0a3778326974d-refs/branch-heads/4324@{#2106}
OS	macOS Version 11.2.1 (Build 20D74)

Steps to verify:

1. enabled ephemeral storage via brave://flags

2. loaded https://dev-pages.brave.software/storage/ephemeral-storage.html
3. clicked Start test
4. verified results matched Step 1: Initial Case example

5. clicked on https://dev-pages.bravesoftware.com/storage/ephemeral-storage.html
6. clicked Read Values
7. verified results matched Step 2: Remote Page, Same Session example

8. copied URL and opened new tab for https://dev-pages.bravesoftware.com/storage/ephemeral-storage.html?storage-test=https%3A%2F%2Fdev-pages.brave.software%2Fstorage%2Fephemeral-storage.html%3A%3A0.11300688081960164&ephemeral-storage-setting=ON&cookie-blocking-setting=BLOCK_THIRD_PARTY
9. verified results matched Step 3: Remote Page, New Session example

10. clicked link in Step 4
11. clicked Read Values
12. verified results matched Step 4: This Page, Same Session Case example

13. copied URL and opened new tab for https://dev-pages.brave.software/storage/ephemeral-storage.html?storage-test=https%3A%2F%2Fdev-pages.brave.software%2Fstorage%2Fephemeral-storage.html%3A%3A0.11300688081960164&ephemeral-storage-setting=ON&cookie-blocking-setting=BLOCK_THIRD_PARTY
14. clicked Read Values
15. verified results matched Step 5: This Page, Different Session

16. closed all test tabs/windows but left unrelated tab/window open (do NOT quite Brave)
17. copied URL and opened new tab for https://dev-pages.brave.software/storage/ephemeral-storage.html?storage-test=https%3A%2F%2Fdev-pages.brave.software%2Fstorage%2Fephemeral-storage.html%3A%3A0.11300688081960164&ephemeral-storage-setting=ON&cookie-blocking-setting=BLOCK_THIRD_PARTY
18. clicked Read Values
19. verified results matched Step 6: New Page, Reset Session Case

20. clicked Reset Test
21. verified test values were reset

---

Verification passed on

Brave	1.21.64 Chromium: 88.0.4324.182 (Official Build) beta (64-bit)
Revision	73ee5087001dcef33047c4ed650471b225dd8caf-refs/branch-heads/4324@{#2202}
OS	Ubuntu 18.04 LTS

Verified testplan from #12789 (comment)

Step 1: Initial Case

Step 2: Remote Page, Same Session

Step 3: Remote Page, New Session

Step 4: This Page, Same Session Case

Step 5: This Page, Different Session

Step 6: New Page, Reset Session Case

Step 7: Clean Up

---

Verification passed on

Brave | 1.21.63 Chromium: 88.0.4324.182 (Official Build) dev (64-bit)
-- | --
Revision | 73ee5087001dcef33047c4ed650471b225dd8caf-refs/branch-heads/4324@{#2202}
OS | Windows 10 OS Version 2004 (Build 19041.804)

enabled ephemeral storage via brave://flags

Step 1: Initial Case

Step 2: Remote Page, Same Session

Step 3: Remote Page, New Session

Step 4: This Page, Same Session Case

Step 5: This Page, Different Session

Step 6: New Page, Reset Session Case

Step 7: Clean Up

[srirambv]

Removing Android label as a follow up issue is logged #14437

[srirambv]

Verification passed on OnePlus 6T with Android 10 running 1.21.71 x64 build

• Verified enabling Ephemeral storage flag and running through the test on https://dev-pages.brave.software/storage/ephemeral-storage.html worked as expected

Step 1: Initial Case

Step 2: Remote Page, Same Session

Step 3: Remote Page, New Session

Step 4: This Page, Same Session Case

Step 5: This Page, Different Session

Step 6: New Page, Reset Session Case

Step 7: Clean Up