mac: ensure ui::Compositor exists for visible RWHVs

content/browser/renderer_host/render_widget_host_view_mac.mm

Index: content/browser/renderer_host/render_widget_host_view_mac.mm
diff --git a/content/browser/renderer_host/render_widget_host_view_mac.mm b/content/browser/renderer_host/render_widget_host_view_mac.mm
index 384bc26e6c6ce9b9ad80bd1be324c28b90d3a594..d97b8456b056f9a8ba0e57c9f8f4bb4e3caa0878 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.mm
+++ b/content/browser/renderer_host/render_widget_host_view_mac.mm
@@ -599,6 +599,9 @@ RenderWidgetHostViewMac::RenderWidgetHostViewMac(RenderWidgetHost* widget,
         ->GetInputEventRouter()
         ->AddSurfaceIdNamespaceOwner(GetSurfaceIdNamespace(), this);
   }
+
+  if (!render_widget_host_->is_hidden())
+    EnsureBrowserCompositorView();
 }
 
 RenderWidgetHostViewMac::~RenderWidgetHostViewMac() {
@@ -1496,8 +1499,7 @@ void RenderWidgetHostViewMac::OnSwapCompositorFrame(
     gfx::Size dip_size = gfx::ConvertSizeToDIP(scale_factor, pixel_size);
 
     root_layer_->SetBounds(gfx::Rect(dip_size));
-    if (!render_widget_host_->is_hidden()) {
-      EnsureBrowserCompositorView();
+    if (browser_compositor_ && browser_compositor_->compositor()) {

[enne (OOO), 2016/05/26 00:07:06]

I forgot to check if browser compositor also existed here, oops.

       browser_compositor_->compositor()->SetScaleAndSize(
           scale_factor, pixel_size);
     }