Call java SurfaceTextureHelper.dispose from the corresponding C++ destructor.

webrtc/api/java/jni/surfacetexturehelper_jni.h

Index: webrtc/api/java/jni/surfacetexturehelper_jni.h
diff --git a/webrtc/api/java/jni/surfacetexturehelper_jni.h b/webrtc/api/java/jni/surfacetexturehelper_jni.h
index d7a9a7707ab7471009b24ec5e4a6ad9e75d4a7db..f925825538bff47ce83651c434c69a57acfb7922 100644
--- a/webrtc/api/java/jni/surfacetexturehelper_jni.h
+++ b/webrtc/api/java/jni/surfacetexturehelper_jni.h
@@ -30,6 +30,8 @@ namespace webrtc_jni {
 // SurfaceTextureHelper is reference counted to make sure that it is not
 // destroyed while a VideoFrameBuffer is in use.
 // This class is the C++ counterpart of the java class SurfaceTextureHelper.
+// It owns the corresponding java object, and calls the java dispose
+// method when destroyed.
 // Usage:
 // 1. Create an instance of this class.
 // 2. Get the Java SurfaceTextureHelper with GetJavaSurfaceTextureHelper().