Fix unknown sources app install confirmation

Allow the package install confirmation dialog to appear properly after
the user turns on unknown sources. Also fix an incorrect session ID
of -1 being shown in related log warnings.

"Finish PIA if UnknownSourcesListener would like to start a PIA again"
is a change that caused this feature to fail for third-party app stores.
This change resolves that issue.

Issue: calyxos#2081
Test: atest CtsPackageInstallTestCases
Test: Manual: Install a third-party app store e.g. F-Droid. Try to
install an app. Tap Settings on the prompt to configure unknown sources.
Tap to turn on unknown sources. The install confirmation dialog appears.

BUG: 326612529
Change-Id: Idd6667cbd79945d849b74a62122162ae72d99210

packages/PackageInstaller/src/com/android/packageinstaller/PackageInstallerActivity.java

@@ -368,7 +368,7 @@ public class PackageInstallerActivity extends AlertActivity {
             final SessionInfo info = mInstaller.getSessionInfo(sessionId);
             String resolvedPath = info != null ? info.getResolvedBaseApkPath() : null;
             if (info == null || !info.isSealed() || resolvedPath == null) {
-                Log.w(TAG, "Session " + mSessionId + " in funky state; ignoring");
+                Log.w(TAG, "Session " + sessionId + " in funky state; ignoring");
                 finish();
                 return;
             }
@@ -383,7 +383,7 @@ public class PackageInstallerActivity extends AlertActivity {
                     -1 /* defaultValue */);
             final SessionInfo info = mInstaller.getSessionInfo(sessionId);
             if (info == null || !info.isPreApprovalRequested()) {
-                Log.w(TAG, "Session " + mSessionId + " in funky state; ignoring");
+                Log.w(TAG, "Session " + sessionId + " in funky state; ignoring");
                 finish();
                 return;
             }
@@ -797,7 +797,9 @@ public class PackageInstallerActivity extends AlertActivity {
                     // work for the multiple user case, i.e. the caller task user and started
                     // Activity user are not the same. To avoid having multiple PIAs in the task,
                     // finish the current PackageInstallerActivity
-                    finish();
+                    // Because finish() is overridden to set the installation result, we must use
+                    // the original finish() method, or the confirmation dialog fails to appear.
+                    PackageInstallerActivity.super.finish();
                 }
             }, 500);