Annotate libjingle_peerconnection_java with @Nullable.

Bug: webrtc:8881
Change-Id: Ida2ef6c003567d19529c21629c916ed40e8de3a6
Reviewed-on: https://webrtc-review.googlesource.com/63380
Commit-Queue: Sami Kalliomäki <sakal@webrtc.org>
Reviewed-by: Paulina Hensman <phensman@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22563}
diff --git a/sdk/android/api/org/webrtc/VideoFrameDrawer.java b/sdk/android/api/org/webrtc/VideoFrameDrawer.java
index 491fd05..96292ec 100644
--- a/sdk/android/api/org/webrtc/VideoFrameDrawer.java
+++ b/sdk/android/api/org/webrtc/VideoFrameDrawer.java
@@ -13,6 +13,7 @@
 import android.graphics.Matrix;
 import android.graphics.Point;
 import android.opengl.GLES20;
+import javax.annotation.Nullable;
 import java.nio.ByteBuffer;
 
 /**
@@ -55,14 +56,15 @@
     // Intermediate copy buffer for uploading yuv frames that are not packed, i.e. stride > width.
     // TODO(magjed): Investigate when GL_UNPACK_ROW_LENGTH is available, or make a custom shader
     // that handles stride and compare performance with intermediate copy.
-    private ByteBuffer copyBuffer;
-    private int[] yuvTextures;
+    @Nullable private ByteBuffer copyBuffer;
+    @Nullable private int[] yuvTextures;
 
     /**
      * Upload |planes| into OpenGL textures, taking stride into consideration.
      *
      * @return Array of three texture indices corresponding to Y-, U-, and V-plane respectively.
      */
+    @Nullable
     public int[] uploadYuvData(int width, int height, int[] strides, ByteBuffer[] planes) {
       final int[] planeWidths = new int[] {width, width / 2, width / 2};
       final int[] planeHeights = new int[] {height, height / 2, height / 2};
@@ -105,12 +107,14 @@
       return yuvTextures;
     }
 
+    @Nullable
     public int[] uploadFromBuffer(VideoFrame.I420Buffer buffer) {
       int[] strides = {buffer.getStrideY(), buffer.getStrideU(), buffer.getStrideV()};
       ByteBuffer[] planes = {buffer.getDataY(), buffer.getDataU(), buffer.getDataV()};
       return uploadYuvData(buffer.getWidth(), buffer.getHeight(), strides, planes);
     }
 
+    @Nullable
     public int[] getYuvTextures() {
       return yuvTextures;
     }
@@ -144,7 +148,7 @@
   // |renderWidth| and |renderHeight| to avoid allocations since this function is called for every
   // frame.
   private void calculateTransformedRenderSize(
-      int frameWidth, int frameHeight, Matrix renderMatrix) {
+      int frameWidth, int frameHeight, @Nullable Matrix renderMatrix) {
     if (renderMatrix == null) {
       renderWidth = frameWidth;
       renderHeight = frameHeight;
@@ -167,7 +171,7 @@
   private final YuvUploader yuvUploader = new YuvUploader();
   // This variable will only be used for checking reference equality and is used for caching I420
   // textures.
-  private VideoFrame lastI420Frame;
+  @Nullable private VideoFrame lastI420Frame;
   private final Matrix renderMatrix = new Matrix();
 
   public void drawFrame(VideoFrame frame, RendererCommon.GlDrawer drawer) {
@@ -181,7 +185,7 @@
   }
 
   public void drawFrame(VideoFrame frame, RendererCommon.GlDrawer drawer,
-      Matrix additionalRenderMatrix, int viewportX, int viewportY, int viewportWidth,
+      @Nullable Matrix additionalRenderMatrix, int viewportX, int viewportY, int viewportWidth,
       int viewportHeight) {
     final int width = frame.getRotatedWidth();
     final int height = frame.getRotatedHeight();