pt 1 in reviving the android build (copied from pm 28a1, wish me luck)

mobile/android/base/java/org/mozilla/gecko/ActivityHandlerHelper.java

@@ -0,0 +1,61 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.gecko;
+
+import org.mozilla.gecko.util.ActivityResultHandler;
+import org.mozilla.gecko.util.ActivityResultHandlerMap;
+
+import android.app.Activity;
+import android.content.ActivityNotFoundException;
+import android.content.Context;
+import android.content.Intent;
+import android.util.Log;
+
+public class ActivityHandlerHelper {
+    private static final String LOGTAG = "GeckoActivityHandlerHelper";
+    private static final ActivityResultHandlerMap mActivityResultHandlerMap = new ActivityResultHandlerMap();
+
+    private static int makeRequestCode(ActivityResultHandler aHandler) {
+        return mActivityResultHandlerMap.put(aHandler);
+    }
+
+    public static void startIntent(Intent intent, ActivityResultHandler activityResultHandler) {
+        startIntentForActivity(GeckoAppShell.getGeckoInterface().getActivity(), intent, activityResultHandler);
+    }
+
+    /**
+     * Starts the Activity, catching & logging if the Activity fails to start.
+     *
+     * We catch to prevent callers from passing in invalid Intents and crashing the browser.
+     *
+     * @return true if the Activity is successfully started, false otherwise.
+     */
+    public static boolean startIntentAndCatch(final String logtag, final Context context, final Intent intent) {
+        try {
+            context.startActivity(intent);
+            return true;
+        } catch (final ActivityNotFoundException e) {
+            Log.w(logtag, "Activity not found.", e);
+            return false;
+        } catch (final SecurityException e) {
+            Log.w(logtag, "Forbidden to launch activity.", e);
+            return false;
+        }
+    }
+
+    public static void startIntentForActivity(Activity activity, Intent intent, ActivityResultHandler activityResultHandler) {
+        activity.startActivityForResult(intent, mActivityResultHandlerMap.put(activityResultHandler));
+    }
+
+
+    public static boolean handleActivityResult(int requestCode, int resultCode, Intent data) {
+        ActivityResultHandler handler = mActivityResultHandlerMap.getAndRemove(requestCode);
+        if (handler != null) {
+            handler.onActivityResult(resultCode, data);
+            return true;
+        }
+        return false;
+    }
+}