Retract GrTexture*.h & GrRenderTarget*.h from other headers

This does push some additional work (& includes) into the .cpp files.

Change-Id: I27c847e371802270d13594dcc22aae44039990bb
Reviewed-on: https://skia-review.googlesource.com/19660
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
diff --git a/tests/ProxyRefTest.cpp b/tests/ProxyRefTest.cpp
index cd07e18..61e5720 100644
--- a/tests/ProxyRefTest.cpp
+++ b/tests/ProxyRefTest.cpp
@@ -11,10 +11,10 @@
 
 #if SK_SUPPORT_GPU
 #include "GrContextPriv.h"
-#include "GrRenderTargetPriv.h"
 #include "GrRenderTargetProxy.h"
 #include "GrResourceProvider.h"
 #include "GrSurfaceProxy.h"
+#include "GrTexture.h"
 #include "GrTextureProxy.h"
 
 int32_t GrIORefProxy::getProxyRefCnt_TestOnly() const {