Redirecting off-origin navigations in PWAs to CCT.

chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappLauncherActivity.java

Index: chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappLauncherActivity.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappLauncherActivity.java b/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappLauncherActivity.java
index a232f04b66ad689b7d37309dd32e758ad99464f6..2faec72fc74a674bbcf5c0896bfd3677adbdc6eb 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappLauncherActivity.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappLauncherActivity.java
@@ -196,19 +196,17 @@ public class WebappLauncherActivity extends Activity {
         launchIntent.setData(Uri.parse(WebappActivity.WEBAPP_SCHEME + "://" + info.id()));
         launchIntent.setFlags(
                 Intent.FLAG_ACTIVITY_NEW_TASK | ApiCompatibilityUtils.getActivityNewDocumentFlag());
-
-        if (!isWebApk) {
-            // If this is launching from a notification, we want to ensure that the URL being
-            // launched is the URL in the intent. If a paused WebappActivity exists for this id,
-            // then by default it will be focused and we have no way of sending the desired URL to
-            // it (the intent is swallowed). As a workaround, set the CLEAR_TOP flag to ensure that
-            // the existing Activity is cleared and relaunched with this intent.
-            // TODO(dominickn): ideally, we want be able to route an intent to
-            // WebappActivity.onNewIntent instead of restarting the Activity.
-            if (source == ShortcutSource.NOTIFICATION) {
-                launchIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
-            }
-        }
+        // Setting FLAG_ACTIVITY_CLEAR_TOP handles 2 edge cases:
+        // - If a legacy PWA is launching from a notification, we want to ensure that the URL being
+        // launched is the URL in the intent. If a paused WebappActivity exists for this id,
+        // then by default it will be focused and we have no way of sending the desired URL to
+        // it (the intent is swallowed). As a workaround, set the CLEAR_TOP flag to ensure that
+        // the existing Activity handles an update via onNewIntent().
+        // - If a WebAPK is having a CustomTabActivity on top of it in the same Task, and user
+        // clicks a link to takes them back to the scope of a WebAPK, we want to destroy the
+        // CustomTabActivity activity and go back to the WebAPK activity. It is intentional that
+        // Custom Tab will not be reachable with a back button.
+        launchIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
         return launchIntent;
     }