Allow specifying a custom cacheKey to ExtractorMediaSource

Issue: #2201

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=142772885

demo/src/main/assets/media.exolist.json

@@ -229,30 +229,6 @@
         "uri": "https://storage.googleapis.com/wvmedia/cenc/vp9/subsample/24fps/tears/tears_uhd.mpd",
         "drm_scheme": "widevine",
         "drm_license_url": "https://proxy.uat.widevine.com/proxy?provider=widevine_test"
-      },
-      {
-        "name": "WV: Secure Subsample (WebM, VP9 with altref)",
-        "uri": "https://storage.googleapis.com/widevine_test/vp9/sintel_1080p_vp9_altref_subsample/sintel_1080p_vp9_altref_subsample.mpd",
-        "drm_scheme": "widevine",
-        "drm_license_url": "https://widevine-proxy.appspot.com/proxy"
-      },
-      {
-        "name": "WV: Secure Fullsample (WebM, VP9 with altref)",
-        "uri": "https://storage.googleapis.com/widevine_test/vp9/sintel_1080p_vp9_altref_fullsample/sintel_1080p_vp9_altref_fullsample.mpd",
-        "drm_scheme": "widevine",
-        "drm_license_url": "https://widevine-proxy.appspot.com/proxy"
-      },
-      {
-        "name": "WV: Secure Subsample (WebM, VP9 without altref)",
-        "uri": "https://storage.googleapis.com/widevine_test/vp9/sintel_1080p_vp9_noaltref_subsample/sintel_1080p_vp9_noaltref_subsample.mpd",
-        "drm_scheme": "widevine",
-        "drm_license_url": "https://widevine-proxy.appspot.com/proxy"
-      },
-      {
-        "name": "WV: Secure Fullsample (WebM, VP9 without altref)",
-        "uri": "https://storage.googleapis.com/widevine_test/vp9/sintel_1080p_vp9_noaltref_fullsample/sintel_1080p_vp9_noaltref_fullsample.mpd",
-        "drm_scheme": "widevine",
-        "drm_license_url": "https://widevine-proxy.appspot.com/proxy"
       }
     ]
   },

library/src/main/java/com/google/android/exoplayer2/source/ExtractorMediaPeriod.java

@@ -62,6 +62,7 @@ import java.io.IOException;
   private final ExtractorMediaSource.EventListener eventListener;
   private final MediaSource.Listener sourceListener;
   private final Allocator allocator;
+  private final String customCacheKey;
   private final Loader loader;
   private final ExtractorHolder extractorHolder;
   private final ConditionVariable loadCondition;
@@ -101,11 +102,13 @@ import java.io.IOException;
    * @param eventListener A listener of events. May be null if delivery of events is not required.
    * @param sourceListener A listener to notify when the timeline has been loaded.
    * @param allocator An {@link Allocator} from which to obtain media buffer allocations.
+   * @param customCacheKey A custom key that uniquely identifies the original stream. Used for cache
+   *     indexing. May be null.
    */
   public ExtractorMediaPeriod(Uri uri, DataSource dataSource, Extractor[] extractors,
       int minLoadableRetryCount, Handler eventHandler,
       ExtractorMediaSource.EventListener eventListener, MediaSource.Listener sourceListener,
-      Allocator allocator) {
+      Allocator allocator, String customCacheKey) {
     this.uri = uri;
     this.dataSource = dataSource;
     this.minLoadableRetryCount = minLoadableRetryCount;
@@ -113,6 +116,7 @@ import java.io.IOException;
     this.eventListener = eventListener;
     this.sourceListener = sourceListener;
     this.allocator = allocator;
+    this.customCacheKey = customCacheKey;
     loader = new Loader("Loader:ExtractorMediaPeriod");
     extractorHolder = new ExtractorHolder(extractors, this);
     loadCondition = new ConditionVariable();
@@ -615,7 +619,7 @@ import java.io.IOException;
         ExtractorInput input = null;
         try {
           long position = positionHolder.position;
-          length = dataSource.open(new DataSpec(uri, position, C.LENGTH_UNSET, null));
+          length = dataSource.open(new DataSpec(uri, position, C.LENGTH_UNSET, customCacheKey));
           if (length != C.LENGTH_UNSET) {
             length += position;
           }

library/src/main/java/com/google/android/exoplayer2/source/ExtractorMediaSource.java

@@ -93,6 +93,7 @@ public final class ExtractorMediaSource implements MediaSource, MediaSource.List
   private final Handler eventHandler;
   private final EventListener eventListener;
   private final Timeline.Period period;
+  private final String customCacheKey;
 
   private MediaSource.Listener sourceListener;
   private Timeline timeline;
@@ -110,7 +111,25 @@ public final class ExtractorMediaSource implements MediaSource, MediaSource.List
   public ExtractorMediaSource(Uri uri, DataSource.Factory dataSourceFactory,
       ExtractorsFactory extractorsFactory, Handler eventHandler, EventListener eventListener) {
     this(uri, dataSourceFactory, extractorsFactory, MIN_RETRY_COUNT_DEFAULT_FOR_MEDIA, eventHandler,
-        eventListener);
+        eventListener, null);
+  }
+
+  /**
+   * @param uri The {@link Uri} of the media stream.
+   * @param dataSourceFactory A factory for {@link DataSource}s to read the media.
+   * @param extractorsFactory A factory for {@link Extractor}s to process the media stream. If the
+   *     possible formats are known, pass a factory that instantiates extractors for those formats.
+   *     Otherwise, pass a {@link DefaultExtractorsFactory} to use default extractors.
+   * @param eventHandler A handler for events. May be null if delivery of events is not required.
+   * @param eventListener A listener of events. May be null if delivery of events is not required.
+   * @param customCacheKey A custom key that uniquely identifies the original stream. Used for cache
+   *     indexing. May be null.
+   */
+  public ExtractorMediaSource(Uri uri, DataSource.Factory dataSourceFactory,
+      ExtractorsFactory extractorsFactory, Handler eventHandler, EventListener eventListener,
+      String customCacheKey) {
+    this(uri, dataSourceFactory, extractorsFactory, MIN_RETRY_COUNT_DEFAULT_FOR_MEDIA, eventHandler,
+        eventListener, customCacheKey);
   }
 
   /**
@@ -122,16 +141,19 @@ public final class ExtractorMediaSource implements MediaSource, MediaSource.List
    * @param minLoadableRetryCount The minimum number of times to retry if a loading error occurs.
    * @param eventHandler A handler for events. May be null if delivery of events is not required.
    * @param eventListener A listener of events. May be null if delivery of events is not required.
+   * @param customCacheKey A custom key that uniquely identifies the original stream. Used for cache
+   *     indexing. May be null.
    */
   public ExtractorMediaSource(Uri uri, DataSource.Factory dataSourceFactory,
       ExtractorsFactory extractorsFactory, int minLoadableRetryCount, Handler eventHandler,
-      EventListener eventListener) {
+      EventListener eventListener, String customCacheKey) {
     this.uri = uri;
     this.dataSourceFactory = dataSourceFactory;
     this.extractorsFactory = extractorsFactory;
     this.minLoadableRetryCount = minLoadableRetryCount;
     this.eventHandler = eventHandler;
     this.eventListener = eventListener;
+    this.customCacheKey = customCacheKey;
     period = new Timeline.Period();
   }
 
@@ -152,7 +174,7 @@ public final class ExtractorMediaSource implements MediaSource, MediaSource.List
     Assertions.checkArgument(index == 0);
     return new ExtractorMediaPeriod(uri, dataSourceFactory.createDataSource(),
         extractorsFactory.createExtractors(), minLoadableRetryCount, eventHandler, eventListener,
-        this, allocator);
+        this, allocator, customCacheKey);
   }
 
   @Override