Rename flushForExternalRead->flushForExternalIO and always call in SkSurface::getTextureHandle

src/gpu/GrSurface.cpp

Index: src/gpu/GrSurface.cpp
diff --git a/src/gpu/GrSurface.cpp b/src/gpu/GrSurface.cpp
index b304ccb1ddbff9d2d9de3c2f010258bcd6ade72b..9685c5627567589acf91685f706b2cb73b0efd3f 100644
--- a/src/gpu/GrSurface.cpp
+++ b/src/gpu/GrSurface.cpp
@@ -84,9 +84,9 @@ void GrSurface::flushWrites() {
     }
 }
 
-void GrSurface::prepareForExternalRead() {
+void GrSurface::prepareForExternalIO() {
     if (!this->wasDestroyed()) {
-        this->getContext()->prepareSurfaceForExternalRead(this);
+        this->getContext()->prepareSurfaceForExternalIO(this);
     }
 }