Move getPeriodPosition methods to Timeline

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=160273929

library/core/src/main/java/com/google/android/exoplayer2/ExoPlayerImplInternal.java

@@ -1128,7 +1128,7 @@ import java.io.IOException;
     // Map the SeekPosition to a position in the corresponding timeline.
     Pair<Integer, Long> periodPosition;
     try {
-      periodPosition = getPeriodPosition(seekTimeline, seekPosition.windowIndex,
+      periodPosition = seekTimeline.getPeriodPosition(window, period, seekPosition.windowIndex,
           seekPosition.windowPositionUs);
     } catch (IndexOutOfBoundsException e) {
       // The window index of the seek position was outside the bounds of the timeline.
@@ -1157,53 +1157,11 @@ import java.io.IOException;
   }
 
   /**
-   * Calls {@link #getPeriodPosition(Timeline, int, long)} using the current timeline.
+   * Calls {@link Timeline#getPeriodPosition(Timeline.Window, Timeline.Period, int, long)} using the
+   * current timeline.
    */
   private Pair<Integer, Long> getPeriodPosition(int windowIndex, long windowPositionUs) {
-    return getPeriodPosition(timeline, windowIndex, windowPositionUs);
+    return timeline.getPeriodPosition(window, period, windowIndex, windowPositionUs);
-  }
-
-  /**
-   * Calls {@link #getPeriodPosition(Timeline, int, long, long)} with a zero default position
-   * projection.
-   */
-  private Pair<Integer, Long> getPeriodPosition(Timeline timeline, int windowIndex,
-      long windowPositionUs) {
-    return getPeriodPosition(timeline, windowIndex, windowPositionUs, 0);
-  }
-
-  /**
-   * Converts (windowIndex, windowPositionUs) to the corresponding (periodIndex, periodPositionUs).
-   *
-   * @param timeline The timeline containing the window.
-   * @param windowIndex The window index.
-   * @param windowPositionUs The window time, or {@link C#TIME_UNSET} to use the window's default
-   *     start position.
-   * @param defaultPositionProjectionUs If {@code windowPositionUs} is {@link C#TIME_UNSET}, the
-   *     duration into the future by which the window's position should be projected.
-   * @return The corresponding (periodIndex, periodPositionUs), or null if {@code #windowPositionUs}
-   *     is {@link C#TIME_UNSET}, {@code defaultPositionProjectionUs} is non-zero, and the window's
-   *     position could not be projected by {@code defaultPositionProjectionUs}.
-   */
-  private Pair<Integer, Long> getPeriodPosition(Timeline timeline, int windowIndex,
-      long windowPositionUs, long defaultPositionProjectionUs) {
-    Assertions.checkIndex(windowIndex, 0, timeline.getWindowCount());
-    timeline.getWindow(windowIndex, window, false, defaultPositionProjectionUs);
-    if (windowPositionUs == C.TIME_UNSET) {
-      windowPositionUs = window.getDefaultPositionUs();
-      if (windowPositionUs == C.TIME_UNSET) {
-        return null;
-      }
-    }
-    int periodIndex = window.firstPeriodIndex;
-    long periodPositionUs = window.getPositionInFirstPeriodUs() + windowPositionUs;
-    long periodDurationUs = timeline.getPeriod(periodIndex, period).getDurationUs();
-    while (periodDurationUs != C.TIME_UNSET && periodPositionUs >= periodDurationUs
-        && periodIndex < window.lastPeriodIndex) {
-      periodPositionUs -= periodDurationUs;
-      periodDurationUs = timeline.getPeriod(++periodIndex, period).getDurationUs();
-    }
-    return Pair.create(periodIndex, periodPositionUs);
   }
 
   private void updatePeriods() throws ExoPlaybackException, IOException {
@@ -1349,8 +1307,8 @@ import java.io.IOException;
         long defaultPositionProjectionUs = loadingPeriodHolder.getRendererOffset()
             + timeline.getPeriod(loadingPeriodHolder.periodIndex, period).getDurationUs()
             - rendererPositionUs;
-        Pair<Integer, Long> defaultPosition = getPeriodPosition(timeline, newLoadingWindowIndex,
+        Pair<Integer, Long> defaultPosition = timeline.getPeriodPosition(window, period,
-            C.TIME_UNSET, Math.max(0, defaultPositionProjectionUs));
+            newLoadingWindowIndex, C.TIME_UNSET, Math.max(0, defaultPositionProjectionUs));
         if (defaultPosition == null) {
           return;
         }

library/core/src/main/java/com/google/android/exoplayer2/Timeline.java

@@ -15,6 +15,9 @@
  */
 package com.google.android.exoplayer2;
 
+import android.util.Pair;
+import com.google.android.exoplayer2.util.Assertions;
+
 /**
  * A representation of media currently available for playback.
  * <p>
@@ -521,6 +524,50 @@ public abstract class Timeline {
     return getPeriod(periodIndex, period, false);
   }
 
+  /**
+   * Calls {@link #getPeriodPosition(Window, Period, int, long, long)} with a zero default position
+   * projection.
+   */
+  public final Pair<Integer, Long> getPeriodPosition(Window window, Period period, int windowIndex,
+      long windowPositionUs) {
+    return getPeriodPosition(window, period, windowIndex, windowPositionUs, 0);
+  }
+
+  /**
+   * Converts (windowIndex, windowPositionUs) to the corresponding (periodIndex, periodPositionUs).
+   *
+   * @param window A {@link Window} that may be overwritten.
+   * @param period A {@link Period} that may be overwritten.
+   * @param windowIndex The window index.
+   * @param windowPositionUs The window time, or {@link C#TIME_UNSET} to use the window's default
+   *     start position.
+   * @param defaultPositionProjectionUs If {@code windowPositionUs} is {@link C#TIME_UNSET}, the
+   *     duration into the future by which the window's position should be projected.
+   * @return The corresponding (periodIndex, periodPositionUs), or null if {@code #windowPositionUs}
+   *     is {@link C#TIME_UNSET}, {@code defaultPositionProjectionUs} is non-zero, and the window's
+   *     position could not be projected by {@code defaultPositionProjectionUs}.
+   */
+  public final Pair<Integer, Long> getPeriodPosition(Window window, Period period, int windowIndex,
+      long windowPositionUs, long defaultPositionProjectionUs) {
+    Assertions.checkIndex(windowIndex, 0, getWindowCount());
+    getWindow(windowIndex, window, false, defaultPositionProjectionUs);
+    if (windowPositionUs == C.TIME_UNSET) {
+      windowPositionUs = window.getDefaultPositionUs();
+      if (windowPositionUs == C.TIME_UNSET) {
+        return null;
+      }
+    }
+    int periodIndex = window.firstPeriodIndex;
+    long periodPositionUs = window.getPositionInFirstPeriodUs() + windowPositionUs;
+    long periodDurationUs = getPeriod(periodIndex, period).getDurationUs();
+    while (periodDurationUs != C.TIME_UNSET && periodPositionUs >= periodDurationUs
+        && periodIndex < window.lastPeriodIndex) {
+      periodPositionUs -= periodDurationUs;
+      periodDurationUs = getPeriod(++periodIndex, period).getDurationUs();
+    }
+    return Pair.create(periodIndex, periodPositionUs);
+  }
+
   /**
    * Populates a {@link Period} with data for the period at the specified index.
    *