Prevents TransactionTooLargeException error in WebViewActivity

RELEASE-NOTES.txt

@@ -10,6 +10,7 @@
 * [*] [Jetpack-only] Site Monitoring: Add Metrics, PHP Logs, and Web Server Logs under Site Monitoring [https://github.com/wordpress-mobile/WordPress-Android/issues/20067]
 * [**] Prevent images from temporarily disappearing when uploading media [https://github.com/WordPress/gutenberg/pull/57869]
 * [***] [Jetpack-only] Reader: introduced new UI/UX for content navigation and filtering [https://github.com/wordpress-mobile/WordPress-Android/pull/19978]
+* [**] Prevents crashes when the webview state is too big [https://github.com/wordpress-mobile/WordPress-Android/pull/20139]
 
 24.1
 -----

WordPress/src/main/java/org/wordpress/android/ui/WebViewActivity.java

@@ -14,8 +14,10 @@
 
 import org.wordpress.android.R;
 import org.wordpress.android.WordPress;
+import org.wordpress.android.analytics.AnalyticsTracker;
 import org.wordpress.android.util.extensions.CompatExtensionsKt;
 
+import java.util.HashMap;
 import java.util.Map;
 
 /**
@@ -28,6 +30,9 @@ public abstract class WebViewActivity extends LocaleAwareActivity {
 
     private static final String URL = "url";
 
+    private static final String WEBVIEW_CHROMIUM_STATE = "WEBVIEW_CHROMIUM_STATE";
+    private static final int WEBVIEW_CHROMIUM_STATE_THRESHOLD = 300 * 1024; // 300 KB
+
     protected WebView mWebView;
 
     @Override
@@ -84,18 +89,43 @@ protected void loadContent() {
      * save the webView state with the bundle so it can be restored
      */
     @Override
-    protected void onSaveInstanceState(Bundle outState) {
+    protected void onSaveInstanceState(@NonNull Bundle outState) {
         mWebView.saveState(outState);
+
+        // If the WebView state is too large, remove it from the bundle and track the error. This workaround is
+        // necessary since the Android system cannot handle large states without a crash.
+        // Note that Chromium `WebViewBrowserFragment` uses a similar workaround for this issue:
+        // https://source.chromium.org/chromium/chromium/src/+/27a9bbd3dcd7005ac9f3862dc2e356b557023de9
+        byte[] webViewState = outState.getByteArray(WEBVIEW_CHROMIUM_STATE);
+        if (webViewState != null && webViewState.length > WEBVIEW_CHROMIUM_STATE_THRESHOLD) {
+            outState.remove(WEBVIEW_CHROMIUM_STATE);
+
+            // Save the URL so it can be restored later
+            String url = mWebView.getUrl();
+            outState.putString(URL, url);
+
+            // Track the error to better understand the root of the issue
+            Map<String, String> properties = new HashMap<>();
+            properties.put(URL, url);
+            AnalyticsTracker.track(AnalyticsTracker.Stat.WEBVIEW_TOO_LARGE_PAYLOAD_ERROR, properties);
+        }
         super.onSaveInstanceState(outState);
     }
 
     /*
      * restore the webView state saved above
      */
     @Override
-    protected void onRestoreInstanceState(Bundle savedInstanceState) {
+    protected void onRestoreInstanceState(@NonNull Bundle savedInstanceState) {
         super.onRestoreInstanceState(savedInstanceState);
-        mWebView.restoreState(savedInstanceState);
+        if (savedInstanceState.containsKey(WEBVIEW_CHROMIUM_STATE)) {
+            mWebView.restoreState(savedInstanceState);
+        } else {
+            String url = savedInstanceState.getString(URL);
+            if (url != null) {
+                mWebView.loadUrl(url);
+            }
+        }
     }
 
     @Override

libs/analytics/src/main/java/org/wordpress/android/analytics/AnalyticsTracker.java

@@ -1106,7 +1106,8 @@ public enum Stat {
         SITE_MONITORING_SCREEN_SHOWN,
         OPENED_SITE_MONITORING,
         SITE_MONITORING_TAB_SHOWN,
-        SITE_MONITORING_TAB_LOADING_ERROR
+        SITE_MONITORING_TAB_LOADING_ERROR,
+        WEBVIEW_TOO_LARGE_PAYLOAD_ERROR,
     }
 
     private static final List<Tracker> TRACKERS = new ArrayList<>();

libs/analytics/src/main/java/org/wordpress/android/analytics/AnalyticsTrackerNosara.java

@@ -2707,6 +2707,8 @@ public static String getEventNameForStat(AnalyticsTracker.Stat stat) {
                 return "site_monitoring_tab_shown";
             case SITE_MONITORING_TAB_LOADING_ERROR:
                 return "site_monitoring_tab_loading_error";
+            case WEBVIEW_TOO_LARGE_PAYLOAD_ERROR:
+                return "webview_too_large_payload_error";
         }
         return null;
     }