[DevTools] Implement screen size and position in Emulation.setDeviceMetricsOverrides.

content/renderer/render_widget.cc

Index: content/renderer/render_widget.cc
diff --git a/content/renderer/render_widget.cc b/content/renderer/render_widget.cc
index ff314be36cba567af9beb0eb5d1a0de4e4ca688f..d1faa54257c0519bda8f426527876ed0955f7e7a 100644
--- a/content/renderer/render_widget.cc
+++ b/content/renderer/render_widget.cc
@@ -378,9 +378,14 @@ void RenderWidget::ScreenMetricsEmulator::Apply(
     widget_->screen_info_.availableRect = original_screen_info_.availableRect;
     widget_->window_screen_rect_ = original_window_screen_rect_;
   } else {
-    applied_widget_rect_.set_origin(gfx::Point(0, 0));
-    widget_->screen_info_.rect = applied_widget_rect_;
-    widget_->screen_info_.availableRect = applied_widget_rect_;
+    applied_widget_rect_.set_origin(params_.viewPosition);
+    gfx::Rect screen_rect = applied_widget_rect_;
+    if (!params_.screenSize.isEmpty()) {
+      screen_rect =
+          gfx::Rect(0, 0, params_.screenSize.width, params_.screenSize.height);
+    }
+    widget_->screen_info_.rect = screen_rect;
+    widget_->screen_info_.availableRect = screen_rect;
     widget_->window_screen_rect_ = applied_widget_rect_;
   }