Querying robustnesslevel from CDM instead of hardcoding the levels.

[kkanag314]

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< bug title >
https://bugs.webkit.org/show_bug.cgi?id=#####
Reviewed by NOBODY (OOPS!).
Explanation of why this fixes the bug (OOPS!).
* path/changed.ext:
(function):
(class.function):

9d4da06

Build-Tests	Layout-Tests
✅ 🛠 wpe-246-amd64-build	✅ 🧪 wpe-246-amd64-layout
✅ 🛠 wpe-246-arm32-build	✅ 🧪 wpe-246-arm32-layout

[eocanha]

Thanks for your contribution, Krishna.

It would be nice to explain briefly the purpose of the patch in the PR description. That would help me to understand its rationale and review it in a more efficient way.
Also, please join both commits in a single one and write a commit message that explains a bit what the purpose of the commit is and what it does. You can use git rebase -i b5686e7^ (that's the previous commit to the first one in the branch) and mark the second commit of the branch as "f" (fix) of the first one.

Thank you so much.

[eocanha]

This condition (was better in its original !m_thunderSystem shape, because an early return is the preferred way to manage error cases in WebKit (when reasonable).

You can have a first "CDMPrivateThunder: No active OpenCDM system..." warning (not error) message about the check for no thunder system, and then a later "Failed to get robustness levels..." warning message to check for a successful robustness level retrieval. In both cases, you would need to return { emptyAtom(), "SW_SECURE_DECODE"_s, "SW_SECURE_CRYPTO"_s };. You can declare that default value as a constant that you can use from the two return places if you want.

[eocanha]

This kind of one-line "then" clauses in ifs and other control structures (this one and the other ones in the same overall block) shouldn't have braces, as per the WebKit coding style guide.