Media Session API: use MediaMetadata in the browser process.

content/public/android/java/src/org/chromium/content_public/common/MediaMetadata.java

Index: content/public/android/java/src/org/chromium/content_public/common/MediaMetadata.java
diff --git a/content/public/android/java/src/org/chromium/content_public/common/MediaMetadata.java b/content/public/android/java/src/org/chromium/content_public/common/MediaMetadata.java
new file mode 100644
index 0000000000000000000000000000000000000000..fc58e18a56eac62a6f39bfbc2b79cbe25a4689d0
--- /dev/null
+++ b/content/public/android/java/src/org/chromium/content_public/common/MediaMetadata.java
@@ -0,0 +1,68 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.content_public.common;
+
+import org.chromium.base.annotations.CalledByNative;
+import org.chromium.base.annotations.JNINamespace;
+
+/**
+ * The MediaMetadata class carries information related to a media session. It is
+ * the Java counterpart of content::MediaMetadata.
+ */
+@JNINamespace("content")
+public class MediaMetadata {
+
+    /**
+     * Title associated to the media session.
+     */
+    public String title;

[Ted C, 2016/03/01 17:18:11]

Can these be final?

Not a big fan of mutable member variables, so if not please add accessors and
modifiers.

[mlamouri (slow - plz ping), 2016/03/16 15:47:16]

Hmm, I guess I tried to use this like a struct (ie. the C++ class is a struct).

Changed to be a proper class.

+
+    /**
+     * Artist name associated to the media session.
+     */
+    public String artist;
+
+    /**
+     * Album name associated to the media session.
+     */
+    public String album;
+
+    /*
+     * Creates a new MediaMetadat from the C++ code. This is exactly like the
+     * constructor below apart that it can be called by native code.
+     */
+    @CalledByNative
+    private static MediaMetadata create(String title, String artist, String album) {
+        return new MediaMetadata(title, artist, album);
+    }
+
+    /**
+     * Creates a new MediaMetadata.
+     */
+    public MediaMetadata(String title, String artist, String album) {
+        this.title = title;

[Ted C, 2016/03/01 17:18:11]

from my comment earlier in the change, there is nothing stating that these can
not be null.  If you want to enforce that, I would add comments to artist,
album, etc... that specify it (or just add @NonNull)

Also, I would probably change the constructor to ensure it as well.

this.title = title == null ? "" : title;
...

For example, you check for null in hashCode but not in equals.

Granted if you don't care about these being null, then I would change the
earlier changes to pass null and then say what fields can be null.

[mlamouri (slow - plz ping), 2016/03/16 15:47:16]

Done. Used @NonNull and checked values coming from JNI (@NonNull doesn't work on
@CalledByNative).

+        this.artist = artist;
+        this.album = album;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (obj == this) return true;
+        if (!(obj instanceof MediaMetadata)) return false;
+
+        MediaMetadata other = (MediaMetadata) obj;
+        return title.equals(other.title)

[Ted C, 2016/03/01 17:18:11]

Use TextUtils.equals

[mlamouri (slow - plz ping), 2016/03/16 15:47:16]

Done.

+                && artist.equals(other.artist)
+                && album.equals(other.album);
+    }
+
+    @Override
+    public int hashCode() {
+        int result = title == null ? 0 : title.hashCode();
+        result = 31 * result + (artist == null ? 0 : artist.hashCode());
+        result = 31 * result + (album == null ? 0 : album.hashCode());
+        return result;
+    }
+}