Fix MobileHarness playback tests.

This change fixes various issues:
 - MobileHarness sometimes allocated devices with SDK < 16. As we have no tests running
   on these SDKs, a new dimension filter for the mobile_test target ensures that only
   devices with SDK >= 16 are selected. A similar filter for SDK version is also added
   to the ABR playback tests to ensure no old devices are selected.
 - DRM specific tests are skipped for Api < 18, but were not able to run because the
   DashTestRunner class tried to link to the MediaDrm constructor. Moved the
   constructor to a seperate Builder class to allow execution on Api levels 16 and 17.
 - DashWidevineOfflineTest also tried to access code for Api >= 18 without checking
   the current level.
 - Action implementations which are waiting for events did not ensure that they have a
   nextAction to wait for. This caused NullPointerExceptions when this next action was
   scheduled.
 - DefaultDrmSession always restored the offline keys when a new license was requested,
   even if the keys were already restored. These repeated slow calls to restoreKeys
   resulted in high numbers of dropped buffers.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=171974859

library/core/src/main/java/com/google/android/exoplayer2/drm/DefaultDrmSession.java

@@ -296,26 +296,24 @@ import java.util.UUID;
       case DefaultDrmSessionManager.MODE_QUERY:
         if (offlineLicenseKeySetId == null) {
           postKeyRequest(ExoMediaDrm.KEY_TYPE_STREAMING, allowRetry);
-        } else {
+        } else if (state == STATE_OPENED_WITH_KEYS || restoreKeys()) {
-          if (restoreKeys()) {
+          long licenseDurationRemainingSec = getLicenseDurationRemainingSec();
-            long licenseDurationRemainingSec = getLicenseDurationRemainingSec();
+          if (mode == DefaultDrmSessionManager.MODE_PLAYBACK
-            if (mode == DefaultDrmSessionManager.MODE_PLAYBACK
+              && licenseDurationRemainingSec <= MAX_LICENSE_DURATION_TO_RENEW) {
-                && licenseDurationRemainingSec <= MAX_LICENSE_DURATION_TO_RENEW) {
+            Log.d(TAG, "Offline license has expired or will expire soon. "
-              Log.d(TAG, "Offline license has expired or will expire soon. "
+                + "Remaining seconds: " + licenseDurationRemainingSec);
-                  + "Remaining seconds: " + licenseDurationRemainingSec);
+            postKeyRequest(ExoMediaDrm.KEY_TYPE_OFFLINE, allowRetry);
-              postKeyRequest(ExoMediaDrm.KEY_TYPE_OFFLINE, allowRetry);
+          } else if (licenseDurationRemainingSec <= 0) {
-            } else if (licenseDurationRemainingSec <= 0) {
+            onError(new KeysExpiredException());
-              onError(new KeysExpiredException());
+          } else {
-            } else {
+            state = STATE_OPENED_WITH_KEYS;
-              state = STATE_OPENED_WITH_KEYS;
+            if (eventHandler != null && eventListener != null) {
-              if (eventHandler != null && eventListener != null) {
+              eventHandler.post(new Runnable() {
-                eventHandler.post(new Runnable() {
+                @Override
-                  @Override
+                public void run() {
-                  public void run() {
+                  eventListener.onDrmKeysRestored();
-                    eventListener.onDrmKeysRestored();
+                }
-                  }
+              });
-                });
-              }
             }
           }
         }

playbacktests/src/androidTest/java/com/google/android/exoplayer2/playbacktests/gts/DashTestRunner.java

@@ -108,21 +108,23 @@ public final class DashTestRunner {
   private String widevineLicenseUrl;
   private DataSource.Factory dataSourceFactory;
 
-  @TargetApi(18)
   @SuppressWarnings("ResourceType")
   public static boolean isL1WidevineAvailable(String mimeType) {
-    try {
+    if (Util.SDK_INT >= 18) {
-      // Force L3 if secure decoder is not available.
+      try {
-      if (MediaCodecUtil.getDecoderInfo(mimeType, true) == null) {
+        // Force L3 if secure decoder is not available.
-        return false;
+        if (MediaCodecUtil.getDecoderInfo(mimeType, true) == null) {
+          return false;
+        }
+        MediaDrm mediaDrm = MediaDrmBuilder.build();
+        String securityProperty = mediaDrm.getPropertyString(SECURITY_LEVEL_PROPERTY);
+        mediaDrm.release();
+        return WIDEVINE_SECURITY_LEVEL_1.equals(securityProperty);
+      } catch (MediaCodecUtil.DecoderQueryException e) {
+        throw new IllegalStateException(e);
       }
-      MediaDrm mediaDrm = new MediaDrm(WIDEVINE_UUID);
-      String securityProperty = mediaDrm.getPropertyString(SECURITY_LEVEL_PROPERTY);
-      mediaDrm.release();
-      return WIDEVINE_SECURITY_LEVEL_1.equals(securityProperty);
-    } catch (MediaCodecUtil.DecoderQueryException | UnsupportedSchemeException e) {
-      throw new IllegalStateException(e);
     }
+    return false;
   }
 
   public DashTestRunner(String tag, HostActivity activity, Instrumentation instrumentation) {
@@ -457,4 +459,21 @@ public final class DashTestRunner {
 
   }
 
+  /**
+   * Creates a new {@code MediaDrm} object. The encapsulation ensures that the tests can be
+   * executed for API level < 18.
+   */
+  @TargetApi(18)
+  private static final class MediaDrmBuilder {
+
+    public static MediaDrm build () {
+      try {
+        return new MediaDrm(WIDEVINE_UUID);
+      } catch (UnsupportedSchemeException e) {
+        throw new IllegalStateException(e);
+      }
+    }
+
+  }
+
 }

playbacktests/src/androidTest/java/com/google/android/exoplayer2/playbacktests/gts/DashWidevineOfflineTest.java

@@ -67,8 +67,10 @@ public final class DashWidevineOfflineTest extends ActivityInstrumentationTestCa
     boolean useL1Widevine = DashTestRunner.isL1WidevineAvailable(MimeTypes.VIDEO_H264);
     String widevineLicenseUrl = DashTestData.getWidevineLicenseUrl(true, useL1Widevine);
     httpDataSourceFactory = new DefaultHttpDataSourceFactory(USER_AGENT);
-    offlineLicenseHelper = OfflineLicenseHelper.newWidevineInstance(widevineLicenseUrl,
+    if (Util.SDK_INT >= 18) {
-        httpDataSourceFactory);
+      offlineLicenseHelper = OfflineLicenseHelper.newWidevineInstance(widevineLicenseUrl,
+          httpDataSourceFactory);
+    }
   }
 
   @Override

testutils/src/main/java/com/google/android/exoplayer2/testutil/Action.java

@@ -322,6 +322,9 @@ public abstract class Action {
     protected void doActionAndScheduleNextImpl(final SimpleExoPlayer player,
         final MappingTrackSelector trackSelector, final Surface surface, final Handler handler,
         final ActionNode nextAction) {
+      if (nextAction == null) {
+        return;
+      }
       Player.EventListener listener = new Player.DefaultEventListener() {
         @Override
         public void onTimelineChanged(Timeline timeline, Object manifest) {
@@ -362,6 +365,9 @@ public abstract class Action {
     protected void doActionAndScheduleNextImpl(final SimpleExoPlayer player,
         final MappingTrackSelector trackSelector, final Surface surface, final Handler handler,
         final ActionNode nextAction) {
+      if (nextAction == null) {
+        return;
+      }
       player.addListener(new Player.DefaultEventListener() {
         @Override
         public void onPositionDiscontinuity(@Player.DiscontinuityReason int reason) {
@@ -399,6 +405,9 @@ public abstract class Action {
     protected void doActionAndScheduleNextImpl(final SimpleExoPlayer player,
         final MappingTrackSelector trackSelector, final Surface surface, final Handler handler,
         final ActionNode nextAction) {
+      if (nextAction == null) {
+        return;
+      }
       if (targetPlaybackState == player.getPlaybackState()) {
         nextAction.schedule(player, trackSelector, surface, handler);
       } else {
@@ -438,6 +447,9 @@ public abstract class Action {
     protected void doActionAndScheduleNextImpl(final SimpleExoPlayer player,
         final MappingTrackSelector trackSelector, final Surface surface, final Handler handler,
         final ActionNode nextAction) {
+      if (nextAction == null) {
+        return;
+      }
       player.addListener(new Player.DefaultEventListener() {
         @Override
         public void onSeekProcessed() {