surfaceflinger: use Vulkan coordinate system

In Vulkan coordinate system, (0, 0) always maps to memory address 0.
In GL coordinate system, (0, 0) maps to the bottom-left corner.  The
two agree when doing offscreen rendering.  But when rendering to a
window, GL maps (0, 0) to memory address (winHeight-1)*rowStride,
because that is where the bottom-left pixel is.

Let's pick the simpler one for RenderEngine in preparation for
multiple backends.  As a result, we don't need yswap when rendering
to offscreen buffers (it is hidden behind the RenderEngine API).  It
also makes no sense to flip Y coordinate for both vertex postions
and the viewing volume.

Test: chrome, youtube, camera, screen rotation, screenshots, recents
Change-Id: I6d6317bac3de6f208700a67e518011362c600ced
diff --git a/services/surfaceflinger/RenderEngine/gl/GLES20RenderEngine.h b/services/surfaceflinger/RenderEngine/gl/GLES20RenderEngine.h
index c830184..e6a7a00 100644
--- a/services/surfaceflinger/RenderEngine/gl/GLES20RenderEngine.h
+++ b/services/surfaceflinger/RenderEngine/gl/GLES20RenderEngine.h
@@ -62,8 +62,8 @@
 
 protected:
     virtual void dump(String8& result);
-    virtual void setViewportAndProjection(size_t vpw, size_t vph, Rect sourceCrop, size_t hwh,
-                                          bool yswap, ui::Transform::orientation_flags rotation);
+    virtual void setViewportAndProjection(size_t vpw, size_t vph, Rect sourceCrop,
+                                          ui::Transform::orientation_flags rotation);
     virtual void setupLayerBlending(bool premultipliedAlpha, bool opaque, bool disableTexture,
                                     const half4& color) override;
 
@@ -108,6 +108,8 @@
     // with PQ or HLG transfer function.
     bool isHdrDataSpace(const ui::Dataspace dataSpace) const;
     bool needsXYZTransformMatrix() const;
+
+    bool mRenderToFbo = false;
 };
 
 }  // namespace gl