[Android CCT] Do not use StartupTabPreloader's tab for POST share intent

This CL fixes the LoadUrlParams matching in
CustomTabActivityTabController#maybeTakeTabFromStartupTabPreloader()
and does not use StartupTabPreloader's tab if the CCT was launched
as a result of a POST share intent.

BUG=1035752

Change-Id: Ib0e3c4dde6811f85848fffbf585e6e2faea62038
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1974864Reviewed-by: Peter Conn <peconn@chromium.org>
Commit-Queue: Peter Kotwicz <pkotwicz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#729779}

chrome/android/java/src/org/chromium/chrome/browser/customtabs/content/CustomTabActivityTabController.java

@@ -14,6 +14,7 @@ import android.view.Window;
 import androidx.annotation.IntDef;
 import androidx.annotation.Nullable;
 import androidx.browser.customtabs.CustomTabsSessionToken;
+import androidx.browser.trusted.sharing.ShareTarget;
 
 import org.chromium.base.metrics.RecordHistogram;
 import org.chromium.chrome.browser.ActivityTabProvider;
@@ -256,6 +257,15 @@ public class CustomTabActivityTabController
         // Don't overwrite any pre-existing tab.
         if (mTabProvider.getTab() != null) return null;
 
+        ShareTarget shareTarget = mIntentDataProvider.getShareTarget();
+        if (mIntentDataProvider.getShareData() != null && shareTarget != null
+                && ShareTarget.METHOD_POST.equals(shareTarget.method)) {
+            // The navigation is likely a POST (We don't do a POST navigation if the POST
+            // target is outside of the TWA scope.) This does not match
+            // StartupTabPreloader's GET navigation.
+            return null;
+        }
+
         LoadUrlParams loadUrlParams = new LoadUrlParams(mIntentDataProvider.getUrlToLoad());
         String referrer = mConnection.getReferrer(mSession, mIntent);
         if (referrer != null && !referrer.isEmpty()) {