[Android] Scope preloads to activity

[kiftio]

What changes are you making?

A preloaded CheckoutWebView is now only reused when the Context passed to checkoutViewFor resolves to the same Activity instance that was used during ShopifyCheckoutKit.preload. Previously, the cache matched solely on URL, meaning a preloaded view could be handed to a different Activity, leading to potential context mismatches and memory leaks.

The PreloadCache now stores the Activity alongside the cached entry and performs a referential equality check (===) on take. A new findActivity() extension unwraps ContextWrapper chains to locate the backing Activity, so callers passing wrapped contexts (e.g. theme wrappers) continue to benefit from the preload cache. If the resolved Activity differs from the one used during preload, or if the context has no backing Activity at all, the cached view is discarded and checkout loads normally.

How to test

1. Preload a checkout URL from ActivityA, then present it from the same ActivityA — the cached WebView should be reused.
2. Preload a checkout URL from ActivityA, then present it from a different ActivityB — the cached WebView should be discarded and a fresh load should occur.
3. Preload a checkout URL, then present it using a ContextWrapper wrapping the same activity — the cached WebView should still be reused.
4. Preload a checkout URL, then present it using an application context (no backing Activity) — the cached WebView should be discarded.
5. Run the new unit tests: checkout view consumes cached preload when context wraps preload activity, checkout view discards cached preload created by a different activity, and checkout view discards cached preload when context has no activity.

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Before you merge

Important

• I've added tests to support my implementation
• I have read and agree with the Contribution Guidelines
• I have read and agree with the Code of Conduct
• I've updated the relevant platform README (platforms/swift/README.md and/or platforms/android/README.md)

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Releasing a new Swift version?

• I have bumped the version in ShopifyCheckoutKit.podspec
• I have bumped the version in platforms/swift/Sources/ShopifyCheckoutKit/ShopifyCheckoutKit.swift
• I have updated the SwiftPM/CocoaPods version snippets in platforms/swift/README.md (major version only)

Releasing a new Embedded Checkout Protocol version?

• I have bumped embeddedCheckoutProtocolAndroid in platforms/android/gradle/libs.versions.toml
• I have updated protocol/languages/kotlin/embedded-checkout-protocol/api/embedded-checkout-protocol.api if the public API changed

Releasing a new Android version?

• I have bumped checkoutKitAndroid in platforms/android/gradle/libs.versions.toml
• I have updated the Gradle/Maven version snippets in platforms/android/README.md

Tip

See the Contributing documentation for the full release process per platform.

[kiftio]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• [Android] Scope preloads to activity #460 👈 (View in Graphite)
• [Android] Dogfood ShopifyCheckout view in sample #457
• [Android] Extract and expose ShopifyCheckout view #456
• [Android] Replace JavascriptInterface with WebMessageListener #424 : 1 other dependent PR (#446 )
• main

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