Maintain call time across SRVCC (2/3).

When an IMS conference call encounters an SRVCC event requiring a
fallback to GSM/CDMA, we need to maintain the call time for the
conference host across this fallback. So, adding a connectTime attribute
in the underlying conference host's connection object which can be used
to account for the call time from the now inactive conference call into
the new call created.

BUG: 21918593
Change-Id: I13e7ae6e31f004e798776c02ac7a6ac09a10f0bd

telecomm/java/android/telecom/Connection.java

@@ -1050,6 +1050,7 @@ public abstract class Connection extends Conferenceable {
     private int mConnectionCapabilities;
     private VideoProvider mVideoProvider;
     private boolean mAudioModeIsVoip;
+    private long mConnectTimeMillis = Conference.CONNECT_TIME_NOT_SPECIFIED;
     private StatusHints mStatusHints;
     private int mVideoState;
     private DisconnectCause mDisconnectCause;
@@ -1161,6 +1162,19 @@ public abstract class Connection extends Conferenceable {
         return mAudioModeIsVoip;
     }
 
+    /**
+     * Retrieves the connection start time of the {@code Connnection}, if specified.  A value of
+     * {@link Conference#CONNECT_TIME_NOT_SPECIFIED} indicates that Telecom should determine the
+     * start time of the conference.
+     *
+     * @return The time at which the {@code Connnection} was connected.
+     *
+     * @hide
+     */
+    public final long getConnectTimeMillis() {
+        return mConnectTimeMillis;
+    }
+
     /**
      * @return The status hints for this connection.
      */
@@ -1475,6 +1489,18 @@ public abstract class Connection extends Conferenceable {
         }
     }
 
+    /**
+     * Sets the time at which a call became active on this Connection. This is set only
+     * when a conference call becomes active on this connection.
+     *
+     * @param connectionTimeMillis The connection time, in milliseconds.
+     *
+     * @hide
+     */
+    public final void setConnectTimeMillis(long connectTimeMillis) {
+        mConnectTimeMillis = connectTimeMillis;
+    }
+
     /**
      * Sets the label and icon status to display in the in-call UI.
      *