Adds DevTools commands for forced viewport override.

content/renderer/gpu/render_widget_compositor.cc

Index: content/renderer/gpu/render_widget_compositor.cc
diff --git a/content/renderer/gpu/render_widget_compositor.cc b/content/renderer/gpu/render_widget_compositor.cc
index 9aed1cfadca523e1f983fd21db2151ee8b38b7a3..61b5e466388935a3c9dbdee0fac5a4f351c7e3d4 100644
--- a/content/renderer/gpu/render_widget_compositor.cc
+++ b/content/renderer/gpu/render_widget_compositor.cc
@@ -710,6 +710,10 @@ void RenderWidgetCompositor::setViewportSize(
   layer_tree_host_->GetLayerTree()->SetViewportSize(device_viewport_size);
 }
 
+WebSize RenderWidgetCompositor::getViewportSize() const {
+  return layer_tree_host_->GetLayerTree()->device_viewport_size();
+}
+
 WebFloatPoint RenderWidgetCompositor::adjustEventPointForPinchZoom(
     const WebFloatPoint& point) const {
   return point;
@@ -719,6 +723,10 @@ void RenderWidgetCompositor::setDeviceScaleFactor(float device_scale) {
   layer_tree_host_->GetLayerTree()->SetDeviceScaleFactor(device_scale);
 }
 
+float RenderWidgetCompositor::getDeviceScaleFactor() const {
+  return layer_tree_host_->GetLayerTree()->device_scale_factor();
+}
+
 void RenderWidgetCompositor::setBackgroundColor(blink::WebColor color) {
   layer_tree_host_->GetLayerTree()->set_background_color(color);
 }