Move /webrtc/api/android files to /webrtc/sdk/android

I decided to make one webrtc/sdk/android/BUILD.gn for both tests and Java/jni src.

External dependencies needs to be updated after this CL.

Future work is required to clean up the Android api and move
implementation details to /webrtc/sdk/android/src.

BUG=webrtc:5882,webrtc:6804
NOPRESUBMIT=True

Review-Url: https://codereview.webrtc.org/2547483003
Cr-Commit-Position: refs/heads/master@{#15443}

webrtc/sdk/android/api/org/webrtc/RtpParameters.java

@@ -0,0 +1,40 @@
+/*
+ *  Copyright 2013 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+package org.webrtc;
+
+import java.util.LinkedList;
+
+/**
+ * The parameters for an {@code RtpSender}, as defined in
+ * http://w3c.github.io/webrtc-pc/#rtcrtpsender-interface.
+ */
+public class RtpParameters {
+  public static class Encoding {
+    public boolean active = true;
+    // A null value means "no maximum bitrate".
+    public Integer maxBitrateBps;
+  }
+
+  public static class Codec {
+    int payloadType;
+    String mimeType;
+    int clockRate;
+    int channels = 1;
+  }
+
+  public final LinkedList<Encoding> encodings;
+  public final LinkedList<Codec> codecs;
+
+  public RtpParameters() {
+    encodings = new LinkedList<Encoding>();
+    codecs = new LinkedList<Codec>();
+  }
+}