Scale Sky contents by the device pixel ratio

On devices with a non-trivial device pixel ratio, we need to tell Sky about the
device pixel ratio so that it can scale up its rendering to the appropriate
size.

R=eseidel@chromium.org, esprehn@chromium.org

Review URL: https://codereview.chromium.org/851533002

sky/viewer/document_view.cc

diff --git a/sky/viewer/document_view.cc b/sky/viewer/document_view.cc
index b8a9a22..8301174 100644
--- a/sky/viewer/document_view.cc
+++ b/sky/viewer/document_view.cc
@@ -22,6 +22,7 @@
 #include "sky/compositor/layer_host.h"
 #include "sky/engine/public/platform/Platform.h"
 #include "sky/engine/public/platform/WebHTTPHeaderVisitor.h"
+#include "sky/engine/public/platform/WebScreenInfo.h"
 #include "sky/engine/public/web/Sky.h"
 #include "sky/engine/public/web/WebConsoleMessage.h"
 #include "sky/engine/public/web/WebDocument.h"
@@ -109,8 +110,11 @@
 
   Load(response_.Pass());
 
-  gfx::Size size = root_->bounds().To<gfx::Rect>().size();
-  web_view_->resize(size);
+  auto& bounds = root_->bounds();
+  float device_pixel_ratio = GetDevicePixelRatio();
+  web_view_->resize(blink::WebSize(bounds.width / device_pixel_ratio,
+                                   bounds.height / device_pixel_ratio));
+
   // TODO(abarth): We should ask the view whether it is focused instead of
   // assuming that we're focused.
   web_view_->setFocus(true);
@@ -151,7 +155,9 @@
   web_view_->beginFrame(web_begin_frame_args);
   web_view_->layout();
   blink::WebSize size = web_view_->size();
-  root_layer_->SetSize(gfx::Size(size.width, size.height));
+  float device_pixel_ratio = GetDevicePixelRatio();
+  root_layer_->SetSize(gfx::Size(size.width * device_pixel_ratio,
+                                 size.height * device_pixel_ratio));
 }
 
 void DocumentView::OnSurfaceIdAvailable(mojo::SurfaceIdPtr surface_id) {
@@ -169,6 +175,16 @@
   layer_host_->SetNeedsAnimate();
 }
 
+blink::WebScreenInfo DocumentView::screenInfo() {
+  DCHECK(root_);
+  auto& metrics = root_->viewport_metrics();
+  blink::WebScreenInfo screen;
+  screen.rect = blink::WebRect(0, 0, metrics.size->width, metrics.size->height);
+  screen.availableRect = screen.rect;
+  screen.deviceScaleFactor = metrics.device_pixel_ratio;
+  return screen;
+}
+
 mojo::View* DocumentView::createChildFrame(const blink::WebURL& url) {
   if (!root_)
     return nullptr;
@@ -186,6 +202,12 @@
   frame->close();
 }
 
+float DocumentView::GetDevicePixelRatio() const {
+  if (root_)
+    return root_->viewport_metrics().device_pixel_ratio;
+  return 1.f;
+}
+
 blink::WebNavigationPolicy DocumentView::decidePolicyForNavigation(
     const blink::WebFrameClient::NavigationPolicyInfo& info) {
 

sky/viewer/document_view.h

diff --git a/sky/viewer/document_view.h b/sky/viewer/document_view.h
index 6494d52..98d8513 100644
--- a/sky/viewer/document_view.h
+++ b/sky/viewer/document_view.h
@@ -76,6 +76,7 @@
   // WebWidgetClient methods:
   void initializeLayerTreeView() override;
   void scheduleAnimation() override;
+  blink::WebScreenInfo screenInfo() override;
 
   // WebFrameClient methods:
   mojo::View* createChildFrame(const blink::WebURL& url) override;
@@ -115,6 +116,7 @@
   void OnViewInputEvent(mojo::View* view, const mojo::EventPtr& event) override;
 
   void Load(mojo::URLResponsePtr response);
+  float GetDevicePixelRatio() const;
 
   mojo::URLResponsePtr response_;
   mojo::ServiceProviderImpl exported_services_;