Android: Deprecated custom matrix helper functions in RendererCommon

All usage of these functions should be migrated to use
android.opengl.Matrix instead.

Bug: webrtc:9487
Change-Id: I023761b31cae7e7af9b537928b849657baa5bb8b
Reviewed-on: https://webrtc-review.googlesource.com/87263
Commit-Queue: Magnus Jedvert <magjed@webrtc.org>
Reviewed-by: Sami Kalliomäki <sakal@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23853}

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

@@ -119,6 +119,7 @@ public class RendererCommon {
   // This limits excessive cropping when adjusting display size.
   private static float BALANCED_VISIBLE_FRACTION = 0.5625f;
   // clang-format off
+  @Deprecated
   public static final float[] identityMatrix() {
     return new float[] {
         1, 0, 0, 0,
@@ -127,6 +128,7 @@ public class RendererCommon {
         0, 0, 0, 1};
   }
   // Matrix with transform y' = 1 - y.
+  @Deprecated
   public static final float[] verticalFlipMatrix() {
     return new float[] {
         1,  0, 0, 0,
@@ -136,6 +138,7 @@ public class RendererCommon {
   }
 
   // Matrix with transform x' = 1 - x.
+  @Deprecated
   public static final float[] horizontalFlipMatrix() {
     return new float[] {
         -1, 0, 0, 0,
@@ -149,6 +152,7 @@ public class RendererCommon {
    * Returns texture matrix that will have the effect of rotating the frame |rotationDegree|
    * clockwise when rendered.
    */
+  @Deprecated
   public static float[] rotateTextureMatrix(float[] textureMatrix, float rotationDegree) {
     final float[] rotationMatrix = new float[16];
     Matrix.setRotateM(rotationMatrix, 0, rotationDegree, 0, 0, 1);
@@ -159,6 +163,7 @@ public class RendererCommon {
   /**
    * Returns new matrix with the result of a * b.
    */
+  @Deprecated
   public static float[] multiplyMatrices(float[] a, float[] b) {
     final float[] resultMatrix = new float[16];
     Matrix.multiplyMM(resultMatrix, 0, a, 0, b, 0);