Alter GrSurface/GrSurfaceProxy flags to prepare for GrTexture/GrTextureProxy -specific flags

This CL:
  moves GrRenderTarget::fFlags to GrSurface::fSurfaceFlags
  adds a GrInternalSurfaceFlags type and uses it for GrSurfaceProxy::fSurfaceFlags

  The goal of this is to provide a location where GrTexture/GrTextureProxy-specific flags
(i.e., isExternal & isRectangle) can be stored.

Change-Id: I8df7b79036a6853dd378ff6cf10d4b37c60dd511
Reviewed-on: https://skia-review.googlesource.com/114796
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/tests/ProxyTest.cpp b/tests/ProxyTest.cpp
index 4970e43..fa53a7a 100644
--- a/tests/ProxyTest.cpp
+++ b/tests/ProxyTest.cpp
@@ -17,6 +17,7 @@
 #include "GrRenderTargetPriv.h"
 #include "GrRenderTargetProxy.h"
 #include "GrResourceProvider.h"
+#include "GrSurfacePriv.h"
 #include "GrSurfaceProxyPriv.h"
 #include "GrTexture.h"
 #include "GrTextureProxy.h"
@@ -72,7 +73,7 @@
     REPORTER_ASSERT(reporter, rt->fsaaType() == rtProxy->fsaaType());
     REPORTER_ASSERT(reporter, rt->numColorSamples() == rtProxy->numColorSamples());
     REPORTER_ASSERT(reporter, rt->numStencilSamples() == rtProxy->numStencilSamples());
-    REPORTER_ASSERT(reporter, rt->renderTargetPriv().flags() == rtProxy->testingOnly_getFlags());
+    REPORTER_ASSERT(reporter, rt->surfacePriv().flags() == rtProxy->testingOnly_getFlags());
 }
 
 static void check_texture(skiatest::Reporter* reporter,