Fix memory leak

src/android/InAppBrowser.java

@@ -160,7 +160,6 @@ public class InAppBrowser extends CordovaPlugin {
      */
     public boolean execute(String action, CordovaArgs args, final CallbackContext callbackContext) throws JSONException {
         if (action.equals("open")) {
-            this.callbackContext = callbackContext;
             final String url = args.getString(0);
             String t = args.optString(1);
             if (t == null || t.equals("") || t.equals(NULL)) {
@@ -171,6 +170,11 @@ public boolean execute(String action, CordovaArgs args, final CallbackContext ca
 
             LOG.d(LOG_TAG, "target = " + target);
 
+            final boolean keepCallback = !SYSTEM.equals(target);
+            if (keepCallback) {
+                this.callbackContext = callbackContext;
+            }
+
             this.cordova.getActivity().runOnUiThread(new Runnable() {
                 @Override
                 public void run() {
@@ -248,7 +252,7 @@ else if (SYSTEM.equals(target)) {
                     }
 
                     PluginResult pluginResult = new PluginResult(PluginResult.Status.OK, result);
-                    pluginResult.setKeepCallback(true);
+                    pluginResult.setKeepCallback(keepCallback);
                     callbackContext.sendPluginResult(pluginResult);
                 }
             });
@@ -265,12 +269,6 @@ else if (action.equals("loadAfterBeforeload")) {
                 @SuppressLint("NewApi")
                 @Override
                 public void run() {
-                    if (android.os.Build.VERSION.SDK_INT < android.os.Build.VERSION_CODES.O) {
-                        currentClient.waitForBeforeload = false;
-                        inAppWebView.setWebViewClient(currentClient);
-                    } else {
-                        ((InAppBrowserClient)inAppWebView.getWebViewClient()).waitForBeforeload = false;
-                    }
                     inAppWebView.loadUrl(url);
                 }
             });
@@ -541,6 +539,16 @@ public void onPageFinished(WebView view, String url) {
                             dialog.dismiss();
                             dialog = null;
                         }
+
+                        // Fix for webView window not being destroyed correctly causing memory leak
+                        // (https://github.com/apache/cordova-plugin-inappbrowser/issues/290)
+                        if (url.equals("about:blank")) {
+                            inAppWebView.onPause();
+                            inAppWebView.removeAllViews();
+                            inAppWebView.destroyDrawingCache();
+                            inAppWebView.destroy();
+                            inAppWebView = null;
+                        }
                     }
                 });
                 // NB: From SDK 19: "If you call methods on WebView from any thread
@@ -1156,7 +1164,6 @@ public class InAppBrowserClient extends WebViewClient {
         EditText edittext;
         CordovaWebView webView;
         String beforeload;
-        boolean waitForBeforeload;
 
         /**
          * Constructor.
@@ -1168,7 +1175,6 @@ public InAppBrowserClient(CordovaWebView webView, EditText mEditText, String bef
             this.webView = webView;
             this.edittext = mEditText;
             this.beforeload = beforeload;
-            this.waitForBeforeload = beforeload != null;
         }
 
         /**
@@ -1229,7 +1235,7 @@ public boolean shouldOverrideUrlLoading(String url, String method) {
             }
 
             // On first URL change, initiate JS callback. Only after the beforeload event, continue.
-            if (useBeforeload && this.waitForBeforeload) {
+            if (useBeforeload) {
                 if(sendBeforeLoad(url, method)) {
                     return true;
                 }
@@ -1324,9 +1330,6 @@ else if (!url.startsWith("http:") && !url.startsWith("https:") && url.matches("^
                 }
             }
 
-            if (useBeforeload) {
-                this.waitForBeforeload = true;
-            }
             return override;
         }