Remove RenderWidget::SetBackground, change IPC to pass a bool.

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 33a0b77f1ef29782e93782f0befff06fafed75c2..788c2c19ad25581b96877137feae78f7884e9086 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -771,10 +771,10 @@ gfx::Rect RenderWidgetHostViewAura::GetViewBounds() const {
   return delegated_frame_host_->GetViewBoundsWithResizeLock(bounds);
 }
 
-void RenderWidgetHostViewAura::SetBackground(const SkBitmap& background) {
-  RenderWidgetHostViewBase::SetBackground(background);
-  host_->SetBackground(background);
-  window_->layer()->SetFillsBoundsOpaquely(background.isOpaque());
+void RenderWidgetHostViewAura::SetBackgroundOpaque(bool opaque) {
+  RenderWidgetHostViewBase::SetBackgroundOpaque(opaque);
+  host_->SetBackgroundOpaque(opaque);
+  window_->layer()->SetFillsBoundsOpaquely(opaque);
 }
 
 gfx::Size RenderWidgetHostViewAura::GetVisibleViewportSize() const {