Snippet for binding Done/Discard Bar pattern via ActivityLifecycleCallbacks.

actionbar_custom_view_done.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
  Copyright 2012 Roman Nurik

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
  -->

<!-- Resembles: ✓ DONE  | -->
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal"
    android:divider="?android:attr/actionBarDivider"
    android:showDividers="end"
    android:dividerPadding="12dp">

    <include layout="@layout/actionbar_done_button" />
</LinearLayout>

actionbar_custom_view_done_discard.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
  Copyright 2012 Roman Nurik

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
  -->

<!-- Resembles: ✕ DISCARD   |   ✓ DONE -->
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal"
    android:divider="?android:actionBarDivider"
    android:showDividers="middle"
    android:dividerPadding="12dp">

    <include layout="@layout/actionbar_discard_button" />
    <include layout="@layout/actionbar_done_button" />
</LinearLayout>

actionbar_discard_button.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
  Copyright 2012 Roman Nurik
  
  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at
  
      http://www.apache.org/licenses/LICENSE-2.0
  
  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
-->

<!-- Done/Discard discard button layout. Resembles: ✕ DISCARD -->
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/actionbar_discard"
    style="?android:actionButtonStyle"
    android:layout_width="0dp"
    android:layout_height="match_parent"
    android:layout_weight="1" >

    <TextView
        style="?android:actionBarTabTextStyle"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:drawableLeft="@drawable/ic_action_discard"
        android:drawablePadding="8dp"
        android:gravity="center_vertical"
        android:paddingRight="20dp"
        android:text="@string/button_discard" />

</FrameLayout>

actionbar_done_button.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
  Copyright 2012 Roman Nurik

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
  -->
  
<!-- Done/Discard done button layout. Resembles: ✓ DONE -->
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    style="?android:actionButtonStyle"
    android:id="@+id/actionbar_done"
    android:layout_width="0dp"
    android:layout_height="match_parent"
    android:layout_weight="1">

    <TextView style="?android:actionBarTabTextStyle"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:paddingRight="20dp"
        android:drawableLeft="@drawable/ic_action_done"
        android:drawablePadding="8dp"
        android:gravity="center_vertical"
        android:text="@string/button_done" />
</FrameLayout>

DoneDiscardCallbacks.java

/*
 * Copyright 2012 Dandre Allison
 *           2012 Roman Nurik
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.imminentmeals.android.base.activity_lifecycle_callbacks;

import javax.annotation.CheckForNull;
import javax.annotation.Nonnegative;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import javax.inject.Inject;

import android.app.ActionBar;
import android.app.Activity;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import butterknife.Views;

import com.imminentmeals.android.base.R;
import com.imminentmeals.android.base.utilities.SimpleActivityLifecycleCallbacks;

/**
 * <p>Defines the callbacks for the Done/Discard Bar pattern and creates the bar for {@link Activity}s that
 * are defined to use it. The Done/Discard Bar was introduced by Roman Nurik in the Google+ post linked below.</p>
 *
 * <p>The pattern is defined to be used in <em>two modes</em>: <b>Done Only</b> mode and Done/Discard mode. The default
 * mode is Done/Discard mode. In Done/Discard mode, the Action Bar is replaced with a custom View that displays two buttons
 * and resembles:
 * <pre>✕ DISCARD   |   ✓ DONE</pre>
 * In Done Only mode the discard button is hidden, it can provided through the Action Overflow menu if desired.
 * <pre>✓ DONE   |</pre>
 *
 * @see <a href="https://plus.google.com/113735310430199015092/posts/R49wVvcDoEW">Roman's Google+ post</a>
 * @see UsesDoneDiscardBar
 * @see UsesDoneDiscardBarDoneOnlyMode
 * @author Dandré Allison
 */
public class DoneDiscardCallbacks extends SimpleActivityLifecycleCallbacks {

    /**
     * <p>Marks the {@link Activity} to use the Done/Discard pattern<p>
     * <pre>✕ DISCARD   |   ✓ DONE</pre>
     * @author Dandré Allison
     */
    public interface UsesDoneDiscardBar extends UsesDoneDiscardBarDoneOnlyMode {
        /**
         * <p>Callback triggered when the "discard" button is clicked. This method doesn't need to call
         * {@link Activity#finish()}, as this is already handled by the Controller.</p>
         */
        void onDiscardClicked();
    }

    /**
     * <p>Marks the {@link Activity} to use the Done/Discard pattern in Done Only Mode.<p>
     * <pre>✓ DONE   |</pre>
     * @author Dandré Allison
     */
    public interface UsesDoneDiscardBarDoneOnlyMode {
        /**
         * <p>Callback triggered when the "done" button is clicked. This method doesn't need to call
         * {@link Activity#finish()}, as this is already handled by the Controller.</p>
         */
        void onDoneClicked();
    }

    /**
     * <p>Marks the {@link Activity} to provide custom icon and/or text for its Done/Discard Bar.</p>
     * @author Dandre Allison
     */
    public interface ProvidesCustomDoneButton {
        /**
         * <p>Provides a custom icon for the done button. If none is provided, the default icon will be used.</p>
         * @return The custom icon for the done button
         */
        @Nullable Drawable doneButtonIcon();
        /**
         * <p>Provides custom text for the done button. If none is provided, the default text will be used.</p>
         * @return The custom text for the done button
         */
        @Nullable CharSequence doneButtonText();
    }

    @Inject
    public DoneDiscardCallbacks() { }

/* Activity Lifecycles */
    @Override
    public void onActivityCreated(final Activity activity, @CheckForNull Bundle icicle) {
        // Defines types that are Activity and the Done/Discard Bar pattern
        /** Type-cast for Done/Discard Done Only mode Activity */
        class DoneDiscardBarDoneOnlyModeActivity extends ActivityWrapper implements UsesDoneDiscardBarDoneOnlyMode {

            DoneDiscardBarDoneOnlyModeActivity() {
                super(activity);
            }

            @Override
            public void onDoneClicked() {
                assert activity instanceof UsesDoneDiscardBarDoneOnlyMode;
                ((UsesDoneDiscardBarDoneOnlyMode) activity).onDoneClicked();
            }
        }
        /** Type-cast for Done/Discard Activity */
        class DoneDiscardBarActivity extends DoneDiscardBarDoneOnlyModeActivity implements UsesDoneDiscardBar {

            @Override
            public void onDiscardClicked() {
                assert activity instanceof UsesDoneDiscardBar;
                ((UsesDoneDiscardBar) activity).onDiscardClicked();
            }
        }

        // NOTE: order matters as anything that implements UsesDoneDiscardBar also implements UsesDoneDiscardBarDoneOnlyMode
        if (activity instanceof UsesDoneDiscardBar)
            createDoneDiscardBar(new DoneDiscardBarActivity(), R.layout.actionbar_custom_view_done_discard);
        else if (activity instanceof UsesDoneDiscardBarDoneOnlyMode)
            createDoneDiscardDoneOnlyBar(new DoneDiscardBarDoneOnlyModeActivity(), R.layout.actionbar_custom_view_done);
    }

/* Helpers */
    /**
     * <p>Defines the {@link Activity} methods that will be successfully delegated to a wrapped Activity, used to type-
     * cast an activity also implement a Done/Discard Bar marker interface.</p>
     * @author Dandre Allison
     */
    private static class ActivityWrapper implements ProvidesCustomDoneButton {

        /**
         * <p>Constructs the {@link ActivityWrapper}.</p>
         */
        public ActivityWrapper(@Nonnull Activity activity) {
            _activity = activity;
        }

        /**
         * <p>Get the Action Bar from the wrapped {@link Activity}.</p>
         * @return The Action Bar
         */
        ActionBar getActionBar() {
            return _activity.getActionBar();
        }

        /**
         * <p>Finishes the wrapped {@link Activity}.</p>
         */
        void finish() {
            _activity.finish();
        }

        /**
         * <p>Indicates when the wrapped {@link Activity} provides a custom done button.</p>
         * @return {@code true} indicates the wrapped activity provides a custom done button
         */
        boolean providesCustomDoneButton() {
            return _activity instanceof ProvidesCustomDoneButton;
        }

        @Override
        public CharSequence doneButtonText() {
            return providesCustomDoneButton()? ((ProvidesCustomDoneButton) _activity).doneButtonText() : null;
        }

        @Override
        public Drawable doneButtonIcon() {
            return providesCustomDoneButton()? ((ProvidesCustomDoneButton) _activity).doneButtonIcon() : null;
        }

        /** The {@link Activity}*/
        private final Activity _activity;
    }

    /**
     * <p>Adds the Done/Discard Bar to the Action Bar.</p>
     * @param activity An activity that is marked to use the Done/Discard Bar
     * @param layout The custom view layout
     * @return The created Done/Discard Bar
     */
    @Nonnull private <T extends ActivityWrapper & UsesDoneDiscardBar> View createDoneDiscardBar(
            @Nonnull final T activity,
            @Nonnegative int layout) {
        final View done_discard_bar = createDoneDiscardDoneOnlyBar(activity, layout);
        done_discard_bar.findViewById(R.id.actionbar_discard).setOnClickListener(
                    new View.OnClickListener() {
                        @Override
                        public void onClick(View _) {
                            // "Discard"
                            activity.onDiscardClicked();
                            activity.finish();
                        }
                    });
        activity.getActionBar().setCustomView(done_discard_bar, new ActionBar.LayoutParams(
                ViewGroup.LayoutParams.MATCH_PARENT,
                ViewGroup.LayoutParams.MATCH_PARENT));
        return done_discard_bar;
    }

    /**
     * <p>Adds the Done/Discard in Done Only mode to the Action Bar.</p>
     * @param activity An activity that is marked to use the Done/Discard Bar in Done Only mode
     * @param layout The custom view layout
     * @return The created Done/Discard Bar
     */
    @Nonnull private <T extends ActivityWrapper & UsesDoneDiscardBarDoneOnlyMode> View createDoneDiscardDoneOnlyBar(
            @Nonnull final T activity,
            @Nonnegative int layout) {
        // Inflates a "Done/Discard" custom action bar view.
        final LayoutInflater inflater = (LayoutInflater) activity.getActionBar().getThemedContext()
                .getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
        final View done_discard_bar = inflater.inflate(layout, null);
        final ViewGroup done_button = Views.findById(done_discard_bar, R.id.actionbar_done);
        // Allows for customization of the done button
        if (activity.providesCustomDoneButton()) {
            final TextView done_button_display = (TextView) done_button.getChildAt(0);
            final CharSequence done_text = ((ProvidesCustomDoneButton) activity).doneButtonText();
            if (done_text != null) done_button_display.setText(done_text);
            final Drawable done_icon = ((ProvidesCustomDoneButton) activity).doneButtonIcon();
            if (done_icon != null) done_button_display.setCompoundDrawablesWithIntrinsicBounds(done_icon, null, null, null);
        }
        done_button.setOnClickListener(
                new View.OnClickListener() {
                    @Override
                    public void onClick(View _) {
                        // "Done"
                        activity.onDoneClicked();
                        activity.finish();
                    }
                });
        activity.getActionBar().setCustomView(done_discard_bar);
        activity.getActionBar().setDisplayOptions(ActionBar.DISPLAY_SHOW_CUSTOM,
                                                  ActionBar.DISPLAY_SHOW_CUSTOM | ActionBar.DISPLAY_SHOW_HOME
                                                  | ActionBar.DISPLAY_SHOW_TITLE);
        return done_discard_bar;
    }
}

ExampleActivity.java

package com.imminentmeals.android.base.ui;

import javax.annotation.CheckForNull;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;

import android.app.Activity;
import android.graphics.drawable.Drawable;
import android.util.Log;

import com.imminentmeals.android.base.activity_lifecycle_callbacks.DoneDiscardCallbacks.ProvidesCustomDoneButton;
import com.imminentmeals.android.base.activity_lifecycle_callbacks.DoneDiscardCallbacks.UsesDoneDiscardBar;

/**
 * <p>Shows an example usage of the Done/Discard Bar pattern implementation provided here. {@link ProvidesCustomDoneButton}
 * can of course be omitted of the default <pre>✓ DONE</pre> is desired. Also, not that you can customize the icon or the 
 * text individually. If Done Only mode is preferred, add "DoneOnlyMode" to the end of {@link UsesDoneDiscardBar} and omit
 * {@link #onDiscardClicked()}.</p>
 * @author Dandré Allison
 */
public class ExampleActivity extends Activity implements UsesDoneDiscardBar, ProvidesCustomDoneButton {

/* Done/Discard Bar Callbacks */
    @Override
    public void onDoneClicked() {
        Log.d("Done/Discard", "done!");
    }

    @Override
    public void onDiscardClicked() {
        Log.d("Done/Discard", "discard!");
    }

/* Provides custom done button */
    @Override
    @Nullable public Drawable doneButtonIcon() {
        return null;
    }

    @Override
    @Nullable public CharSequence doneButtonText() {
        return "confirm";
    }
}

SimpleActivityLifecycleCallbacks.java

package com.imminentmeals.android.base.utilities;

import javax.annotation.CheckForNull;
import javax.annotation.ParametersAreNonnullByDefault;

import android.app.Activity;
import android.app.Application.ActivityLifecycleCallbacks;
import android.os.Bundle;

/**
 * <p>A convenience class to extend when only a subset of all callbacks is needed. This implements all methods
 * in the {@link ActivityLifecycleCallbacks} but does nothing.</p>
 */
@ParametersAreNonnullByDefault
public class SimpleActivityLifecycleCallbacks implements ActivityLifecycleCallbacks {

    @Override
    public void onActivityCreated(Activity activity, @CheckForNull Bundle icicle) { }

    @Override
    public void onActivityStarted(Activity activity) { }

    @Override
    public void onActivityResumed(Activity activity) { }

    @Override
    public void onActivityPaused(Activity activity) { }

    @Override
    public void onActivityStopped(Activity activity) { }

    @Override
    public void onActivitySaveInstanceState(Activity activity, @CheckForNull Bundle icicle) { }

    @Override
    public void onActivityDestroyed(Activity activity) { }
}

Just add registerActivityLifecycleCallbacks(new DoneDiscardCallbacks()); to your Application#onCreate() method.