fix: ensure WebContents before checking draggable region

[codebytere]

Description of Change

Closes #41142

Fixes an issue with potential crashes while closing or interacting with a WebContentsView after its associated WebContents has been cleaned up. We first need to ensure that api_web_contents_ is not nullptr, as is done several other places in the same file.

Checklist

• PR description included and stakeholders cc'd
• npm test passes
• PR release notes describe the change in a way relevant to app developers, and are capitalized, punctuated, and past tense.

Release Notes

Notes: Fixed a potential crash while closing or interacting with a WebContentsView after its associated WebContents has been cleaned up.

[deepak1556]

Something to consider, Crash keys are useful in production crash analysis, we can confirm if it was use-after-free before making the fix.

SCOPED_CRASH_KEY_BOOL("WebContentsView_NCHT", "api_web_contents", api_web_contents_ != nullptr)

[codebytere]

@deepak1556 in local testing I was able to confirm that api_web_contents_ is nullptr when the crash occurs - are you looking for more validation beyond that?

[deepak1556]

Ah not required in that case, I was not sure if the crash was repro'd hence the earlier comment.

[release-clerk]

Release Notes Persisted

Fixed a potential crash while closing or interacting with a WebContentsView after its associated WebContents has been cleaned up.