PROTOTYPE (incomplete): Add quad renderer and stub bits to handle security warnings.

chrome/browser/android/vr_shell/vr_shell_gl.cc

Index: chrome/browser/android/vr_shell/vr_shell_gl.cc
diff --git a/chrome/browser/android/vr_shell/vr_shell_gl.cc b/chrome/browser/android/vr_shell/vr_shell_gl.cc
index 05a6c98fdd8852cc1aff038d50e06eef49145280..10b26e402e5b8cdbd8cfeb2311bb54ea086786fc 100644
--- a/chrome/browser/android/vr_shell/vr_shell_gl.cc
+++ b/chrome/browser/android/vr_shell/vr_shell_gl.cc
@@ -993,36 +993,35 @@ void VrShellGl::DrawElements(const vr::Mat4f& view_proj_matrix,
     vr::Mat4f transform;
     vr::MatrixMul(view_proj_matrix, rect->TransformMatrix(), &transform);
 
+    if (rect->Render(vr_shell_renderer_.get())) {
+      continue;
+    }
     switch (rect->fill) {
-      case Fill::SKIA: {
-        break;
-      }
       case Fill::OPAQUE_GRADIENT: {
-        vr_shell_renderer_->GetTexturedQuadRenderer()->Flush();
         vr_shell_renderer_->GetGradientQuadRenderer()->Draw(
             transform, rect->edge_color, rect->center_color,
             rect->computed_opacity);
+        vr_shell_renderer_->GetTexturedQuadRenderer()->Flush();

[cjgrant, 2017/04/19 16:24:52]

This may not be great, but I think this Flush optimization is not adding
anything right now.

         break;
       }
       case Fill::GRID_GRADIENT: {
-        vr_shell_renderer_->GetTexturedQuadRenderer()->Flush();
         vr_shell_renderer_->GetGradientGridRenderer()->Draw(
             transform, rect->edge_color, rect->center_color,
             rect->gridline_count, rect->computed_opacity);
+        vr_shell_renderer_->GetTexturedQuadRenderer()->Flush();
         break;
       }
       case Fill::CONTENT: {
         gfx::RectF copy_rect(0, 0, 1, 1);
         vr_shell_renderer_->GetTexturedQuadRenderer()->AddQuad(
             content_texture_id_, transform, copy_rect, rect->computed_opacity);
+        vr_shell_renderer_->GetTexturedQuadRenderer()->Flush();
         break;
       }
       default:
         break;
     }
   }
-
-  vr_shell_renderer_->GetTexturedQuadRenderer()->Flush();
 }
 
 std::vector<const UiElement*> VrShellGl::GetElementsInDrawOrder(