title: onBackPressed() method not triggered in AppCompatActivity
body: <p>AppCompatActivity onBackPressed() method fails to trigger in my activity.</p>
  
  <p>I see the back arrow button and get the animation when pressing it, but nothing else happens. also overriding onKeyDown() has the same effect. it's not called.</p>
  
  <p>I've spent many hours researching this with no luck. Nothing seems to work. Anyone has had a similar issue? Maybe this is a known bug?</p>
  
  <p>My Activity.xml:</p>
  
  <pre><code>&lt;RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
  android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
  android:paddingRight="@dimen/activity_horizontal_margin"
  android:paddingTop="@dimen/activity_vertical_margin"
  android:paddingBottom="@dimen/activity_vertical_margin"
  tools:context="com.litenote.android.BackTestingActivity2Activity"&gt;
  &lt;include
      android:id="@+id/appBar"
      layout="@layout/app_bar" /&gt;
  &lt;TextView android:text="@string/hello_world" android:layout_width="wrap_content"
      android:layout_height="wrap_content" /&gt;
  </code></pre>
  
  <p></p>
  
  <p>app_bar.xml</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;android.support.v7.widget.Toolbar xmlns:android="http://schemas.android.com/apk/res/android"
  android:id="@+id/appBar"
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:background="@color/primary"
  android:titleTextAppearance="@color/textWhite"
  android:elevation="4dp"
  android:theme="@style/ThemeOverlay.AppCompat.Dark"
  android:popupTheme="@style/CustomPopupMenuTheme"&gt;
  </code></pre>
  
  <p></p>
  
  <p>The activity Java file</p>
  
  <pre><code>package com.litenote.android;
  
  import android.support.v7.app.ActionBar;
  import android.os.Bundle;
  import android.support.v7.app.AppCompatActivity;
  import android.support.v7.widget.Toolbar;
  import android.util.Log;
  
  import com.superpad.android.R;
  
  public class BackTestingActivity2Activity extends AppCompatActivity {
  
  @Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_back_testing_activity2);
      Toolbar actionBar = ((Toolbar) findViewById(R.id.appBar));
      setSupportActionBar(actionBar);
      getSupportActionBar().setDisplayOptions(ActionBar.DISPLAY_HOME_AS_UP);
      getSupportActionBar().setDisplayShowHomeEnabled(true);
  
  }
  
  @Override
  public void onBackPressed() {
      Log.d("BACK_BUTTON_DOESNT_WORK", "I will never execute and you will never see me :(");
      super.onBackPressed();
      this.finish();
  }
  }
  </code></pre>