I used to write a similar app. I posted my AndroidManifest.xml segment for your reference:
<activity
    android:name=".OpenFileActivity"
    android:configChanges="orientation|keyboardHidden"
    android:label="@string/app_name" >
    <intent-filter>
        <action android:name="android.intent.action.VIEW" >
        </action>
        <category android:name="android.intent.category.DEFAULT" >
        </category>
        <category android:name="android.intent.category.BROWSABLE" >
        </category>
        <data
            android:mimeType="application/pdf"
            android:scheme="file" >
        </data>
    </intent-filter>
    <intent-filter>
        <action android:name="android.intent.action.VIEW" >
        </action>
        <category android:name="android.intent.category.DEFAULT" >
        </category>
        <category android:name="android.intent.category.BROWSABLE" >
        </category>
        <data
            android:mimeType="application/pdf"
            android:scheme="content" >
        </data>
    </intent-filter>
    <intent-filter>
        <action android:name="android.intent.action.VIEW" >
        </action>
        <category android:name="android.intent.category.DEFAULT" >
        </category>
        <category android:name="android.intent.category.BROWSABLE" >
        </category>
        <data
            android:host="*"
            android:pathPattern=".*\.[pP][dD][fF]"
            android:scheme="file" />
    </intent-filter>
</activity>