EglRenderer: Clear texture before drawing a new frame.

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

Index: webrtc/sdk/android/api/org/webrtc/EglRenderer.java
diff --git a/webrtc/sdk/android/api/org/webrtc/EglRenderer.java b/webrtc/sdk/android/api/org/webrtc/EglRenderer.java
index f05f6bc55e45d08a39e93ba19e5dae61cb3c230b..f5c1fe1773ed2465a3fb3c18bb0028b5da0bbeff 100644
--- a/webrtc/sdk/android/api/org/webrtc/EglRenderer.java
+++ b/webrtc/sdk/android/api/org/webrtc/EglRenderer.java
@@ -641,6 +641,8 @@ public class EglRenderer implements VideoRenderer.Callbacks {
       GLES20.glFramebufferTexture2D(GLES20.GL_FRAMEBUFFER, GLES20.GL_COLOR_ATTACHMENT0,
           GLES20.GL_TEXTURE_2D, bitmapTextureFramebuffer.getTextureId(), 0);
 
+      GLES20.glClearColor(0 /* red */, 0 /* green */, 0 /* blue */, 0 /* alpha */);
+      GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
       if (frame.yuvFrame) {
         listenerAndParams.drawer.drawYuv(yuvTextures, bitmapMatrix, frame.rotatedWidth(),
             frame.rotatedHeight(), 0 /* viewportX */, 0 /* viewportY */, scaledWidth, scaledHeight);