TIF: Move watch history logging to TvProvider

There are only two kinds of watch events that can happen on the system:
 1. The current TV input session is tuned to a new channel.
 2. The session is released for some reason.
The former indicates the end of the previous log entry, if any, followed by the
start of a new entry. The latter indicates the end of the most recent entry for
the given session. Here the system supplies the database the smallest set of
information only that is sufficient to consolidate the log entries while
minimizing database operations in the system service.

Bug: 14791151, Bug: 15921205, Bug: 15988715, Bug: 16831555
Change-Id: Ifcb1a1273c14ee234919d819d082b1004eb92ebc

Author: Jae Seo

media/java/android/media/tv/TvContract.java

@@ -21,6 +21,7 @@
 import android.content.ContentResolver;
 import android.content.ContentUris;
 import android.net.Uri;
+import android.os.IBinder;
 import android.provider.BaseColumns;
 import android.util.ArraySet;
 
@@ -795,7 +796,7 @@ public static final class Programs implements BaseTvColumns {
         public static final String CONTENT_ITEM_TYPE = "vnd.android.cursor.item/program";
 
         /**
-         * The ID of the TV channel that contains this TV program.
+         * The ID of the TV channel that provides this TV program.
          * <p>
          * This is a part of the channel URI and matches to {@link BaseColumns#_ID}.
          * </p><p>
@@ -1109,6 +1110,7 @@ public static boolean isCanonical(String genre) {
      * to this table.
      * @hide
      */
+    @SystemApi
     public static final class WatchedPrograms implements BaseTvColumns {
 
         /** The content:// style URI for this table. */
@@ -1141,7 +1143,7 @@ public static final class WatchedPrograms implements BaseTvColumns {
         public static final String COLUMN_WATCH_END_TIME_UTC_MILLIS = "watch_end_time_utc_millis";
 
         /**
-         * The channel ID that contains this TV program.
+         * The ID of the TV channel that provides this TV program.
          * <p>
          * Type: INTEGER (long)
          * </p>
@@ -1181,17 +1183,30 @@ public static final class WatchedPrograms implements BaseTvColumns {
         public static final String COLUMN_DESCRIPTION = "description";
 
         /**
-         * Extra parameters of the tune operation.
+         * Extra parameters given to {@link TvInputService.Session#tune(Uri, android.os.Bundle)
+         * TvInputService.Session.tune(Uri, android.os.Bundle)} when tuning to the channel that
+         * provides this TV program. (Used internally.)
+         * <p>
+         * This column contains an encoded string that represents comma-separated key-value pairs of
+         * the tune parameters. (Ex. "[key1]=[value1], [key2]=[value2]"). '%' is used as an escape
+         * character for '%', '=', and ','.
+         * </p><p>
+         * Type: TEXT
+         * </p>
+         */
+        public static final String COLUMN_INTERNAL_TUNE_PARAMS = "tune_params";
+
+        /**
+         * The session token of this TV program. (Used internally.)
          * <p>
-         * This column contains an encoded string which is comma-separated key-value pairs.
-         * (Ex. "[key1]=[value1], [key2]=[value2]"). COLUMN_TUNE_PARAMS will use '%' as an escape
-         * character for the characters of '%', '=', and ','.
+         * This contains a String representation of {@link IBinder} for
+         * {@link TvInputService.Session} that provides the current TV program. It is used
+         * internally to distinguish watched programs entries from different TV input sessions.
          * </p><p>
          * Type: TEXT
          * </p>
-         * @see TvInputManager.Session.tune(Uri, Bundle)
          */
-        public static final String COLUMN_TUNE_PARAMS = "tune_params";
+        public static final String COLUMN_INTERNAL_SESSION_TOKEN = "session_token";
 
         private WatchedPrograms() {}
     }