cleanup: Remove UnusedVariable in ShellManager

[borongc]

The mStartupUrl member variable, its default value, and the
setStartupUrl method in ShellManager have been removed. This variable
and its associated logic were identified as unused in the Cobalt
application's startup path.

Corresponding usage in CobaltActivity and an unneeded import of
TextUtils have also been removed. This change simplifies the Cobalt
shell code by removing dead code.

Issue: 471083158
Issue: 418842688

Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5921913

[github-actions]

🤖 Gemini Suggested Commit Message

---

android: Remove unused mStartupUrl from ShellManager

The mStartupUrl member variable, its default value, and the
setStartupUrl method in ShellManager have been removed. This variable
and its associated logic were identified as unused in the Cobalt
application's startup path.

Corresponding usage in CobaltActivity and an unneeded import of
TextUtils have also been removed. This change simplifies the Android
shell code by removing dead code.

Bug: 471083158

---

💡 Pro Tips for a Better Commit Message:

1. Influence the Result: Want to change the output? You can write custom prompts or instructions directly in the Pull Request description. The model uses that text to generate the message.
2. Re-run the Generator: Post a comment with: /generate-commit-message

[gemini-code-assist]

Code Review

This pull request correctly removes the unused mStartupUrl variable and its related logic from ShellManager. The changes are clean and focused. However, by removing the usage in CobaltActivity, the mStartupUrl field in that class now appears to be unused after being assigned a value. I've left a comment suggesting this is also cleaned up to make the change more complete.

I am having trouble creating individual review comments. Click here to see my feedback.

cobalt/android/apk/app/src/main/java/dev/cobalt/coat/CobaltActivity.java (173-175)

While removing this block is correct as part of cleaning up ShellManager, it leaves the mStartupUrl field in CobaltActivity as an unused variable. The variable is assigned a value but is no longer read. Please consider also removing the declaration and assignment of mStartupUrl in this class to complete the cleanup.

[Awallky]

LGTM