Android SurfaceViewRenderer: Call glClear() for every frame to avoid bad GL state

talk/app/webrtc/java/android/org/webrtc/SurfaceViewRenderer.java

Index: talk/app/webrtc/java/android/org/webrtc/SurfaceViewRenderer.java
diff --git a/talk/app/webrtc/java/android/org/webrtc/SurfaceViewRenderer.java b/talk/app/webrtc/java/android/org/webrtc/SurfaceViewRenderer.java
index 33ccff29ef5a16b49855833421dee65ddebd45f3..d3e6d67290cc7509238685366652d1c2c67670ea 100644
--- a/talk/app/webrtc/java/android/org/webrtc/SurfaceViewRenderer.java
+++ b/talk/app/webrtc/java/android/org/webrtc/SurfaceViewRenderer.java
@@ -482,6 +482,9 @@ public class SurfaceViewRenderer extends SurfaceView
     }
 
     GLES20.glViewport(0, 0, surfaceWidth, surfaceHeight);
+    // TODO(magjed): glClear() shouldn't be necessary since every pixel is covered anyway, but it's
+    // a workaround for bug 5147. Performance will be slightly worse.
+    GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
     if (frame.yuvFrame) {
       // Make sure YUV textures are allocated.
       if (yuvTextures == null) {