Remove GpuHostMsg_FrameDrawn and replace with client channel swap ack

content/browser/compositor/browser_compositor_output_surface.cc

Index: content/browser/compositor/browser_compositor_output_surface.cc
diff --git a/content/browser/compositor/browser_compositor_output_surface.cc b/content/browser/compositor/browser_compositor_output_surface.cc
index b1e550162f026e98b0046e7698517ba47579e7e8..2aff2545e913355495c6fcca2c1b845825afba1e 100644
--- a/content/browser/compositor/browser_compositor_output_surface.cc
+++ b/content/browser/compositor/browser_compositor_output_surface.cc
@@ -69,11 +69,12 @@ bool BrowserCompositorOutputSurface::BindToClient(
 }
 
 void BrowserCompositorOutputSurface::OnSwapBuffersComplete() {
+#if defined(OS_MACOSX)
   // On Mac, delay acknowledging the swap to the output surface client until
   // it has been drawn.
-#if !defined(OS_MACOSX)
-  cc::OutputSurface::OnSwapBuffersComplete();
+  NOTREACHED();
 #endif
+  cc::OutputSurface::OnSwapBuffersComplete();
 }
 
 void BrowserCompositorOutputSurface::OnUpdateVSyncParameters(