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

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

@@ -0,0 +1,100 @@
+/* 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 android.content.ComponentName;
+import android.content.Intent;
+import android.support.v7.app.AppCompatActivity;
+
+public abstract class GeckoActivity extends AppCompatActivity implements GeckoActivityStatus {
+    // has this activity recently started another Gecko activity?
+    private boolean mGeckoActivityOpened;
+
+    /**
+     * Display any resources that show strings or encompass locale-specific
+     * representations.
+     *
+     * onLocaleReady must always be called on the UI thread.
+     */
+    public void onLocaleReady(final String locale) {
+    }
+
+    @Override
+    public void onPause() {
+        super.onPause();
+
+        if (getApplication() instanceof GeckoApplication) {
+            ((GeckoApplication) getApplication()).onActivityPause(this);
+        }
+    }
+
+    @Override
+    public void onResume() {
+        super.onResume();
+
+        if (getApplication() instanceof GeckoApplication) {
+            ((GeckoApplication) getApplication()).onActivityResume(this);
+            mGeckoActivityOpened = false;
+        }
+    }
+
+    @Override
+    public void onCreate(android.os.Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        if (AppConstants.MOZ_ANDROID_ANR_REPORTER) {
+            ANRReporter.register(getApplicationContext());
+        }
+    }
+
+    @Override
+    public void onDestroy() {
+        if (AppConstants.MOZ_ANDROID_ANR_REPORTER) {
+            ANRReporter.unregister();
+        }
+        super.onDestroy();
+    }
+
+    @Override
+    public void startActivity(Intent intent) {
+        mGeckoActivityOpened = checkIfGeckoActivity(intent);
+        super.startActivity(intent);
+    }
+
+    @Override
+    public void startActivityForResult(Intent intent, int request) {
+        mGeckoActivityOpened = checkIfGeckoActivity(intent);
+        super.startActivityForResult(intent, request);
+    }
+
+    private static boolean checkIfGeckoActivity(Intent intent) {
+        // Whenever we call our own activity, the component and its package name is set.
+        // If we call an activity from another package, or an open intent (leaving android to resolve)
+        // component has a different package name or it is null.
+        ComponentName component = intent.getComponent();
+        return (component != null &&
+                AppConstants.ANDROID_PACKAGE_NAME.equals(component.getPackageName()));
+    }
+
+    @Override
+    public boolean isGeckoActivityOpened() {
+        return mGeckoActivityOpened;
+    }
+
+    public boolean isApplicationInBackground() {
+        return ((GeckoApplication) getApplication()).isApplicationInBackground();
+    }
+
+    @Override
+    public void onLowMemory() {
+        MemoryMonitor.getInstance().onLowMemory();
+        super.onLowMemory();
+    }
+
+    @Override
+    public void onTrimMemory(int level) {
+        MemoryMonitor.getInstance().onTrimMemory(level);
+        super.onTrimMemory(level);
+    }
+}