Use solid color layer for delegated surface.

content/browser/renderer_host/render_widget_host_view_aura.cc

Index: content/browser/renderer_host/render_widget_host_view_aura.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.cc b/content/browser/renderer_host/render_widget_host_view_aura.cc
index 3b8bb93ebc947770f8bf58510255cefc2a5a92a3..dc2478bbf5b4941e4bd5f04fc9ec35ff727740f3 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -474,8 +474,9 @@ RenderWidgetHostViewAura::RenderWidgetHostViewAura(RenderWidgetHost* host)
 void RenderWidgetHostViewAura::InitAsChild(
     gfx::NativeView parent_view) {
   window_->SetType(ui::wm::WINDOW_TYPE_CONTROL);
-  window_->Init(aura::WINDOW_LAYER_TEXTURED);
+  window_->Init(aura::WINDOW_LAYER_SOLID_COLOR);
   window_->SetName("RenderWidgetHostViewAura");
+  window_->layer()->SetColor(SK_ColorWHITE);
 }
 
 void RenderWidgetHostViewAura::InitAsPopup(
@@ -502,8 +503,9 @@ void RenderWidgetHostViewAura::InitAsPopup(
   }
   popup_parent_host_view_->popup_child_host_view_ = this;
   window_->SetType(ui::wm::WINDOW_TYPE_MENU);
-  window_->Init(aura::WINDOW_LAYER_TEXTURED);
+  window_->Init(aura::WINDOW_LAYER_SOLID_COLOR);
   window_->SetName("RenderWidgetHostViewAura");
+  window_->layer()->SetColor(SK_ColorWHITE);
 
   aura::Window* root = popup_parent_host_view_->window_->GetRootWindow();
   aura::client::ParentWindowWithContext(window_, root, bounds_in_screen);
@@ -527,9 +529,10 @@ void RenderWidgetHostViewAura::InitAsFullscreen(
     RenderWidgetHostView* reference_host_view) {
   is_fullscreen_ = true;
   window_->SetType(ui::wm::WINDOW_TYPE_NORMAL);
-  window_->Init(aura::WINDOW_LAYER_TEXTURED);
+  window_->Init(aura::WINDOW_LAYER_SOLID_COLOR);
   window_->SetName("RenderWidgetHostViewAura");
   window_->SetProperty(aura::client::kShowStateKey, ui::SHOW_STATE_FULLSCREEN);
+  window_->layer()->SetColor(SK_ColorWHITE);
 
   aura::Window* parent = NULL;
   gfx::Rect bounds;
@@ -804,6 +807,8 @@ void RenderWidgetHostViewAura::SetBackgroundOpaque(bool opaque) {
   RenderWidgetHostViewBase::SetBackgroundOpaque(opaque);
   host_->SetBackgroundOpaque(opaque);
   window_->layer()->SetFillsBoundsOpaquely(opaque);
+  SkColor background_color = opaque ? SK_ColorWHITE : SK_ColorTRANSPARENT;
+  window_->layer()->SetColor(background_color);
 }
 
 gfx::Size RenderWidgetHostViewAura::GetVisibleViewportSize() const {
@@ -1681,11 +1686,7 @@ void RenderWidgetHostViewAura::OnCaptureLost() {
 }
 
 void RenderWidgetHostViewAura::OnPaint(gfx::Canvas* canvas) {
-  // For non-opaque windows, we don't draw anything, since we depend on the
-  // canvas coming from the compositor to already be initialized as
-  // transparent.
-  if (window_->layer()->fills_bounds_opaquely())
-    canvas->DrawColor(SK_ColorWHITE);
+  DCHECK(false);

[piman, 2014/10/09 06:30:27]

nit: NOTREACHED()

 }
 
 void RenderWidgetHostViewAura::OnDeviceScaleFactorChanged(