API Review cleanups.

- New @SystemApis on Conference and PhoneAccount were missing the required
permissions annotations.
- Rename PROPERTY_ASSISTED_DIALING_USED to PROPERTY_ASSISTED_DIALING
- Standardize get/setConnectionStartElapsedRealtimeMillis method naming
across Connection and Conference classes.
- Clarify Conference#sendConferenceEvent API documentation to match the
docs present for similar method in Connection; include some examples of
valid event/extras combinations.
- Update TelecomManager#getDefaultdialerPackage to use UserHandle instead
of userId.
- Move Conference#getConnectionStartElapsedRealtimeMillis to public API
since the setter is already part of the public API.

Test: Run Telecom and Telephony CTS tests.
Test: Run Telephony unit tests.
Test: Perform manual single-party-conference regression test to confirm
that conference behavior does not regress.

Bug: 147301297
Bug: 148286830
Bug: 148284863
Bug: 148284843
Bug: 148287068
Bug: 148285484
Bug: 148285560
Change-Id: I1f446d81859fa109d74af3661a42a0bd224de5aa
Merged-In: I1f446d81859fa109d74af3661a42a0bd224de5aa
diff --git a/telecomm/java/android/telecom/Conference.java b/telecomm/java/android/telecom/Conference.java
index 6b0845f..97fa2b4 100644
--- a/telecomm/java/android/telecom/Conference.java
+++ b/telecomm/java/android/telecom/Conference.java
@@ -16,8 +16,13 @@
 
 package android.telecom;
 
+import static android.Manifest.permission.MODIFY_PHONE_STATE;
+
+import android.annotation.ElapsedRealtimeLong;
+import android.annotation.IntRange;
 import android.annotation.NonNull;
 import android.annotation.Nullable;
+import android.annotation.RequiresPermission;
 import android.annotation.SystemApi;
 import android.annotation.TestApi;
 import android.net.Uri;
@@ -620,12 +625,12 @@
      * Should be specified in wall-clock time returned by {@link System#currentTimeMillis()}.
      * <p>
      * When setting the connection time, you should always set the connection elapsed time via
-     * {@link #setConnectionStartElapsedRealTime(long)} to ensure the duration is reflected.
+     * {@link #setConnectionStartElapsedRealtimeMillis(long)} to ensure the duration is reflected.
      *
      * @param connectionTimeMillis The connection time, in milliseconds, as returned by
      *                             {@link System#currentTimeMillis()}.
      */
-    public final void setConnectionTime(long connectionTimeMillis) {
+    public final void setConnectionTime(@IntRange(from = 0) long connectionTimeMillis) {
         mConnectTimeMillis = connectionTimeMillis;
     }
 
@@ -641,8 +646,28 @@
      *
      * @param connectionStartElapsedRealTime The connection time, as measured by
      * {@link SystemClock#elapsedRealtime()}.
+     * @deprecated use {@link #setConnectionStartElapsedRealtimeMillis(long)} instead.
      */
+    @Deprecated
     public final void setConnectionStartElapsedRealTime(long connectionStartElapsedRealTime) {
+        setConnectionStartElapsedRealtimeMillis(connectionStartElapsedRealTime);
+    }
+
+    /**
+     * Sets the start time of the {@link Conference} which is the basis for the determining the
+     * duration of the {@link Conference}.
+     * <p>
+     * You should use a value returned by {@link SystemClock#elapsedRealtime()} to ensure that time
+     * zone changes do not impact the conference duration.
+     * <p>
+     * When setting this, you should also set the connection time via
+     * {@link #setConnectionTime(long)}.
+     *
+     * @param connectionStartElapsedRealTime The connection time, as measured by
+     * {@link SystemClock#elapsedRealtime()}.
+     */
+    public final void setConnectionStartElapsedRealtimeMillis(
+            @ElapsedRealtimeLong long connectionStartElapsedRealTime) {
         mConnectionStartElapsedRealTime = connectionStartElapsedRealTime;
     }
 
@@ -663,7 +688,7 @@
      *
      * @return The time at which the {@code Conference} was connected.
      */
-    public final long getConnectionTime() {
+    public final @IntRange(from = 0) long getConnectionTime() {
         return mConnectTimeMillis;
     }
 
@@ -680,11 +705,8 @@
      * has no general use other than to the Telephony framework.
      *
      * @return The elapsed time at which the {@link Conference} was connected.
-     * @hide
      */
-    @SystemApi
-    @TestApi
-    public final long getConnectionStartElapsedRealTime() {
+    public final @ElapsedRealtimeLong long getConnectionStartElapsedRealtimeMillis() {
         return mConnectionStartElapsedRealTime;
     }
 
@@ -981,6 +1003,7 @@
      */
     @SystemApi
     @TestApi
+    @RequiresPermission(MODIFY_PHONE_STATE)
     public void setConferenceState(boolean isConference) {
         for (Listener l : mListeners) {
             l.onConferenceStateChanged(this, isConference);
@@ -1001,6 +1024,7 @@
      */
     @SystemApi
     @TestApi
+    @RequiresPermission(MODIFY_PHONE_STATE)
     public final void setAddress(@NonNull Uri address,
             @TelecomManager.Presentation int presentation) {
         Log.d(this, "setAddress %s", address);
@@ -1107,12 +1131,52 @@
     }
 
     /**
-     * Sends an event associated with this {@code Conference} with associated event extras to the
-     * {@link InCallService} (note: this is identical in concept to
-     * {@link Connection#sendConnectionEvent(String, Bundle)}).
-     * @see Connection#sendConnectionEvent(String, Bundle)
+     * Sends an event associated with this {@link Conference} with associated event extras to the
+     * {@link InCallService}.
+     * <p>
+     * Connection events are used to communicate point in time information from a
+     * {@link ConnectionService} to an {@link InCallService} implementation.  An example of a
+     * custom connection event includes notifying the UI when a WIFI call has been handed over to
+     * LTE, which the InCall UI might use to inform the user that billing charges may apply.  The
+     * Android Telephony framework will send the {@link Connection#EVENT_MERGE_COMPLETE}
+     * connection event when a call to {@link Call#mergeConference()} has completed successfully.
+     * <p>
+     * Events are exposed to {@link InCallService} implementations via
+     * {@link Call.Callback#onConnectionEvent(Call, String, Bundle)}.
+     * <p>
+     * No assumptions should be made as to how an In-Call UI or service will handle these events.
+     * The {@link ConnectionService} must assume that the In-Call UI could even chose to ignore
+     * some events altogether.
+     * <p>
+     * Events should be fully qualified (e.g. {@code com.example.event.MY_EVENT}) to avoid
+     * conflicts between {@link ConnectionService} implementations.  Further, custom
+     * {@link ConnectionService} implementations shall not re-purpose events in the
+     * {@code android.*} namespace, nor shall they define new event types in this namespace.  When
+     * defining a custom event type, ensure the contents of the extras {@link Bundle} is clearly
+     * defined.  Extra keys for this bundle should be named similar to the event type (e.g.
+     * {@code com.example.extra.MY_EXTRA}).
+     * <p>
+     * When defining events and the associated extras, it is important to keep their behavior
+     * consistent when the associated {@link ConnectionService} is updated.  Support for deprecated
+     * events/extras should me maintained to ensure backwards compatibility with older
+     * {@link InCallService} implementations which were built to support the older behavior.
+     * <p>
+     * Expected connection events from the Telephony stack are:
+     * <p>
+     * <ul>
+     *      <li>{@link Connection#EVENT_CALL_HOLD_FAILED} with {@code null} {@code extras} when the
+     *      {@link Conference} could not be held.</li>
+     *      <li>{@link Connection#EVENT_MERGE_START} with {@code null} {@code extras} when a new
+     *      call is being merged into the conference.</li>
+     *      <li>{@link Connection#EVENT_MERGE_COMPLETE} with {@code null} {@code extras} a new call
+     *      has completed being merged into the conference.</li>
+     *      <li>{@link Connection#EVENT_CALL_MERGE_FAILED} with {@code null} {@code extras} a new
+     *      call has failed to merge into the conference (the dialer app can determine which call
+     *      failed to merge based on the fact that the call still exists outside of the conference
+     *      at the end of the merge process).</li>
+     * </ul>
      *
-     * @param event The connection event.
+     * @param event The conference event.
      * @param extras Optional bundle containing extra information associated with the event.
      */
     public void sendConferenceEvent(@NonNull String event, @Nullable Bundle extras) {