[Perf] Add networkInstrumentationEnabled opt-out flag (#8277)

[JesusRojass]

Discussion

Fixes #8277

Adds an Info.plist array key, firebase_performance_swizzle_denylist, that lists class names to skip when registering swizzling instrumentors. Gives developers a way to opt out of swizzling for specific classes that surface leaks through third-party SDKs, without disabling the rest of Firebase Performance.

Usage

Add the key to your app's Info.plist. Each entry is the exact result of NSStringFromClass. To address the URLSession leak described in #8277, deny-list NSURLSession:

<key>firebase_performance_swizzle_denylist</key>
<array>
    <string>NSURLSession</string>
</array>

You can add as many entries as needed. The deny-list applies to any class the SDK tries to swizzle (URLSession, URLConnection, UIViewController, user-supplied delegate classes).

How it works

Enforced at the central swizzle chokepoint, FPRInstrument.registerClassInstrumentor:. If NSStringFromClass(instrumentedClass) is in the deny-list array, the method returns NO and the caller bails before any swizzle is installed. Three routes go through the chokepoint:

• Static class registrations declared by each instrument in registerInstrumentors.
• Subclass discovery at runtime (e.g. +sharedSession and +sessionWithConfiguration: discover __NSCFURLSession and friends).
• User-supplied NSURLSessionDelegate classes registered by FPRNSURLSessionDelegateInstrument.

Strict NSStringFromClass equality, no subclass walk. Read fresh per registration call from Info.plist, no GULUserDefaults mirror, no runtime mutation API.

Testing

All existing tests pass. No new tests added: the deny-list runs at a single line in FPRInstrument.registerClassInstrumentor: and uses standard Info.plist array reading.

API Changes

• No API Changes.

[gemini-code-assist]

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[JesusRojass]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces a networkInstrumentationEnabled property to allow developers to opt-out of automatic URLSession and URLConnection instrumentation while keeping other performance monitoring features active. The setting can be configured via Info.plist, GULUserDefaults, or at runtime, with logic added to FPRConfigurations and FPRClient to handle the conditional registration of network instrumentation. Feedback was provided regarding the documentation style of the new method, suggesting it be made consistent with existing methods for better maintainability.

[JesusRojass]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces a new opt-out mechanism for network instrumentation (URLSession/URLConnection) in the Firebase Performance SDK, configurable via Info.plist or at runtime. The review identified that the getter for the new property should reflect the active state of the SDK rather than just the pending configuration, and suggested simplifying the logic in the isNetworkInstrumentationEnabled method for better readability.

[JesusRojass]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces a networkInstrumentationEnabled configuration option, allowing developers to selectively disable URLSession and URLConnection instrumentation via Info.plist or at runtime. The implementation includes new properties in FPRConfigurations and FPRClient, along with public API updates in FIRPerformance. Review feedback suggests resetting the networkInstrumentationSwizzled flag within disableInstrumentation to ensure consistency during testing and recommends using a more generic error code when settings are modified after the SDK has been configured.