SurfaceTextureClient: Add ISurfaceTexture getter.

This change adds a getter method to SurfaceTextureClient to get the
ISurfaceTexture object with which the SurfaceTextureClient is
communicating.

Bug: 4086509
Change-Id: Ifec621e0fe5392a5be56b2348fdc54067cbebcdd
diff --git a/libs/gui/SurfaceTextureClient.cpp b/libs/gui/SurfaceTextureClient.cpp
index 111141f..7f1d9cb 100644
--- a/libs/gui/SurfaceTextureClient.cpp
+++ b/libs/gui/SurfaceTextureClient.cpp
@@ -40,6 +40,10 @@
     mAllocator = mSurfaceTexture->getAllocator();
 }
 
+sp<ISurfaceTexture> SurfaceTextureClient::getISurfaceTexture() const {
+    return mSurfaceTexture;
+}
+
 int SurfaceTextureClient::setSwapInterval(ANativeWindow* window, int interval) {
     SurfaceTextureClient* c = getSelf(window);
     return c->setSwapInterval(interval);