sync compositor: Set display viewport for software draw

content/renderer/android/synchronous_compositor_output_surface.h

Index: content/renderer/android/synchronous_compositor_output_surface.h
diff --git a/content/renderer/android/synchronous_compositor_output_surface.h b/content/renderer/android/synchronous_compositor_output_surface.h
index 0490b8e57f4535e3b5a90f726e10a1be1c76d157..f95f5353223ae610e2e66faf6fcddbe78f7feb46 100644
--- a/content/renderer/android/synchronous_compositor_output_surface.h
+++ b/content/renderer/android/synchronous_compositor_output_surface.h
@@ -104,6 +104,8 @@ class SynchronousCompositorOutputSurface
   void SetBeginFrameSource(cc::BeginFrameSource* begin_frame_source) override;
 
  private:
+  class SoftwareOutputSurface;
+
   void InvokeComposite(const gfx::Transform& transform,
                        const gfx::Rect& viewport,
                        const gfx::Rect& clip);
@@ -157,6 +159,8 @@ class SynchronousCompositorOutputSurface
   StubDisplayClient display_client_;
   // Uses surface_manager_.
   std::unique_ptr<cc::Display> display_;
+  // Owned by |display_|.
+  SoftwareOutputSurface* software_output_surface_ = nullptr;
 
   base::ThreadChecker thread_checker_;