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/vk/GrVkTextureRenderTarget.h b/src/gpu/vk/GrVkTextureRenderTarget.h
index 7639dc0..7eab105 100644
--- a/src/gpu/vk/GrVkTextureRenderTarget.h
+++ b/src/gpu/vk/GrVkTextureRenderTarget.h
@@ -13,8 +13,6 @@
 #include "GrVkRenderTarget.h"
 #include "GrVkGpu.h"
 
-#include "GrTexturePriv.h"
-
 #ifdef SK_BUILD_FOR_WIN
 // Windows gives bogus warnings about inheriting asTexture/asRenderTarget via dominance.
 #pragma warning(push)
@@ -113,13 +111,7 @@
                                                GrVkImage::Wrapped wrapped);
 
     // GrGLRenderTarget accounts for the texture's memory and any MSAA renderbuffer's memory.
-    size_t onGpuMemorySize() const override {
-        // The plus 1 is to account for the resolve texture.
-        int numColorSamples = this->numColorSamples() + 1;
-        return GrSurface::ComputeSize(this->config(), this->width(), this->height(),
-                                      numColorSamples,  // TODO: this still correct?
-                                      this->texturePriv().hasMipMaps());
-    }
+    size_t onGpuMemorySize() const override;
 };
 
 #endif