Pass through all ID3 internal data from udta

Also switch from using a CommentFrame to a new InternalFrame type for ID3 data
stored with ID '----', to distinguish internal data from actual ID3 comments.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=201315254

RELEASENOTES.md

@@ -31,6 +31,8 @@
   ([#4360](https://github.com/google/ExoPlayer/issues/4360)).
 * Add `PlayerView.isControllerVisible`
   ([#4385](https://github.com/google/ExoPlayer/issues/4385)).
+* Expose all internal ID3 data stored in MP4 udta boxes, and switch from using
+  CommentFrame to InternalFrame for frames with gapless metadata in MP4.
 
 ### 2.8.2 ###
 

library/core/src/main/java/com/google/android/exoplayer2/extractor/GaplessInfoHolder.java

@@ -19,6 +19,7 @@ import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.metadata.Metadata;
 import com.google.android.exoplayer2.metadata.id3.CommentFrame;
 import com.google.android.exoplayer2.metadata.id3.Id3Decoder.FramePredicate;
+import com.google.android.exoplayer2.metadata.id3.InternalFrame;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -39,7 +40,8 @@ public final class GaplessInfoHolder {
     }
   };
 
-  private static final String GAPLESS_COMMENT_ID = "iTunSMPB";
+  private static final String GAPLESS_DOMAIN = "com.apple.iTunes";
+  private static final String GAPLESS_DESCRIPTION = "iTunSMPB";
   private static final Pattern GAPLESS_COMMENT_PATTERN =
       Pattern.compile("^ [0-9a-fA-F]{8} ([0-9a-fA-F]{8}) ([0-9a-fA-F]{8})");
 
@@ -91,7 +93,15 @@ public final class GaplessInfoHolder {
       Metadata.Entry entry = metadata.get(i);
       if (entry instanceof CommentFrame) {
         CommentFrame commentFrame = (CommentFrame) entry;
-        if (setFromComment(commentFrame.description, commentFrame.text)) {
+        if (GAPLESS_DESCRIPTION.equals(commentFrame.description)
+            && setFromComment(commentFrame.text)) {
+          return true;
+        }
+      } else if (entry instanceof InternalFrame) {
+        InternalFrame internalFrame = (InternalFrame) entry;
+        if (GAPLESS_DOMAIN.equals(internalFrame.domain)
+            && GAPLESS_DESCRIPTION.equals(internalFrame.description)
+            && setFromComment(internalFrame.text)) {
           return true;
         }
       }
@@ -103,14 +113,10 @@ public final class GaplessInfoHolder {
    * Populates the holder with data parsed from a gapless playback comment (stored in an ID3 header
    * or MPEG 4 user data), if valid and non-zero.
    *
-   * @param name The comment's identifier.
    * @param data The comment's payload data.
    * @return Whether the holder was populated.
    */
-  private boolean setFromComment(String name, String data) {
-    if (!GAPLESS_COMMENT_ID.equals(name)) {
-      return false;
-    }
+  private boolean setFromComment(String data) {
     Matcher matcher = GAPLESS_COMMENT_PATTERN.matcher(data);
     if (matcher.find()) {
       try {

library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/MetadataUtil.java

@@ -20,6 +20,7 @@ import com.google.android.exoplayer2.metadata.Metadata;
 import com.google.android.exoplayer2.metadata.id3.ApicFrame;
 import com.google.android.exoplayer2.metadata.id3.CommentFrame;
 import com.google.android.exoplayer2.metadata.id3.Id3Frame;
+import com.google.android.exoplayer2.metadata.id3.InternalFrame;
 import com.google.android.exoplayer2.metadata.id3.TextInformationFrame;
 import com.google.android.exoplayer2.util.ParsableByteArray;
 import com.google.android.exoplayer2.util.Util;
@@ -293,14 +294,13 @@ import com.google.android.exoplayer2.util.Util;
         data.skipBytes(atomSize - 12);
       }
     }
-    if (!"com.apple.iTunes".equals(domain) || !"iTunSMPB".equals(name) || dataAtomPosition == -1) {
-      // We're only interested in iTunSMPB.
+    if (domain == null || name == null || dataAtomPosition == -1) {
       return null;
     }
     data.setPosition(dataAtomPosition);
     data.skipBytes(16); // size (4), type (4), version (1), flags (3), empty (4)
     String value = data.readNullTerminatedString(dataAtomSize - 16);
-    return new CommentFrame(LANGUAGE_UNDEFINED, name, value);
+    return new InternalFrame(domain, name, value);
   }
 
   private static int parseUint8AttributeValue(ParsableByteArray data) {

library/core/src/main/java/com/google/android/exoplayer2/metadata/id3/InternalFrame.java

@@ -0,0 +1,96 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.exoplayer2.metadata.id3;
+
+import android.os.Parcel;
+import android.support.annotation.Nullable;
+import com.google.android.exoplayer2.util.Assertions;
+import com.google.android.exoplayer2.util.Util;
+
+/** Internal ID3 frame that is intended for use by the player. */
+public final class InternalFrame extends Id3Frame {
+
+  public static final String ID = "----";
+
+  public final String domain;
+  public final String description;
+  public final String text;
+
+  public InternalFrame(String domain, String description, String text) {
+    super(ID);
+    this.domain = domain;
+    this.description = description;
+    this.text = text;
+  }
+
+  /* package */ InternalFrame(Parcel in) {
+    super(ID);
+    domain = Assertions.checkNotNull(in.readString());
+    description = Assertions.checkNotNull(in.readString());
+    text = Assertions.checkNotNull(in.readString());
+  }
+
+  @Override
+  public boolean equals(@Nullable Object obj) {
+    if (this == obj) {
+      return true;
+    }
+    if (obj == null || getClass() != obj.getClass()) {
+      return false;
+    }
+    InternalFrame other = (InternalFrame) obj;
+    return Util.areEqual(description, other.description)
+        && Util.areEqual(domain, other.domain)
+        && Util.areEqual(text, other.text);
+  }
+
+  @Override
+  public int hashCode() {
+    int result = 17;
+    result = 31 * result + (domain != null ? domain.hashCode() : 0);
+    result = 31 * result + (description != null ? description.hashCode() : 0);
+    result = 31 * result + (text != null ? text.hashCode() : 0);
+    return result;
+  }
+
+  @Override
+  public String toString() {
+    return id + ": domain=" + domain + ", description=" + description;
+  }
+
+  // Parcelable implementation.
+
+  @Override
+  public void writeToParcel(Parcel dest, int flags) {
+    dest.writeString(id);
+    dest.writeString(domain);
+    dest.writeString(text);
+  }
+
+  public static final Creator<InternalFrame> CREATOR =
+      new Creator<InternalFrame>() {
+
+        @Override
+        public InternalFrame createFromParcel(Parcel in) {
+          return new InternalFrame(in);
+        }
+
+        @Override
+        public InternalFrame[] newArray(int size) {
+          return new InternalFrame[size];
+        }
+      };
+}