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/src/gpu/GrDrawOpAtlas.cpp b/src/gpu/GrDrawOpAtlas.cpp
index 78f6ba4..37bad65 100644
--- a/src/gpu/GrDrawOpAtlas.cpp
+++ b/src/gpu/GrDrawOpAtlas.cpp
@@ -11,6 +11,7 @@
 #include "GrOpFlushState.h"
 #include "GrRectanizer.h"
 #include "GrResourceProvider.h"
+#include "GrTexture.h"
 #include "GrTracing.h"
 
 std::unique_ptr<GrDrawOpAtlas> GrDrawOpAtlas::Make(GrContext* ctx, GrPixelConfig config,