Merge "Clarify documentation for notification a11y events" into oc-dev

 * <b>NOTIFICATION TYPES</b></br>

 * </p>

 * <p>

 * <b>Notification state changed</b> - represents the event showing

 * {@link android.app.Notification}.</br>

 * <b>Notification state changed</b> - represents the event showing a transient piece of information

 * to the user. This information may be a {@link android.app.Notification} or

 * {@link android.widget.Toast}.</br>

 * <em>Type:</em> {@link #TYPE_NOTIFICATION_STATE_CHANGED}</br>

 * <em>Properties:</em></br>

 * <ul>

 *   <li>{@link #getClassName()} - The class name of the source.</li>

 *   <li>{@link #getPackageName()} - The package name of the source.</li>

 *   <li>{@link #getEventTime()}  - The event time.</li>

 *   <li>{@link #getParcelableData()} - The posted {@link android.app.Notification}.</li>

 *   <li>{@link #getText()} - Text for providing more context.</li>

 *   <li>{@link #getParcelableData()} - The posted {@link android.app.Notification}, if

 *   applicable.</li>

 *   <li>{@link #getText()} - Displayed text of the {@link android.widget.Toast}, if applicable,

 *   or may contain text from the {@link android.app.Notification}, although

 *   {@link #getParcelableData()} is a richer set of data for {@link android.app.Notification}.</li>

 * </ul>

 * <em>Note:</em> This event type is not dispatched to descendants though

 * {@link android.view.View#dispatchPopulateAccessibilityEvent(AccessibilityEvent)

 * View.dispatchPopulateAccessibilityEvent(AccessibilityEvent)}, hence the event

 * source {@link android.view.View} and the sub-tree rooted at it will not receive

 * calls to {@link android.view.View#onPopulateAccessibilityEvent(AccessibilityEvent)

 * View.onPopulateAccessibilityEvent(AccessibilityEvent)}. The preferred way to add

 * text content to such events is by setting the

 * {@link android.R.styleable#View_contentDescription contentDescription} of the source

 * view.</br>

 * </p>

 * <p>

 * <b>EXPLORATION TYPES</b></br>