NaCl SDK: Demonstrate use of pp::View::GetDeviceScale for 3D

Demonstrate in the NaCl SDK API demo for pp::Graphics3D how to
use full device resolution on HiDPI displays. For Graphics3D it
is simply a matter of sizing the texture in device pixels, by
multiplying the width/height by view.GetDeviceScale().

BUG=196253
TEST=Build NaCl SDK, run with --force-device-scale-factor=2

Review URL: https://codereview.chromium.org/398943003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@283952 0039d316-1c4b-4281-b951-d872f2087c98

native_client_sdk/src/examples/api/graphics_3d/graphics_3d.cc

@@ -247,8 +247,11 @@ class Graphics3DInstance : public pp::Instance {
   }
 
   virtual void DidChangeView(const pp::View& view) {
-    int32_t new_width = view.GetRect().width();
-    int32_t new_height = view.GetRect().height();
+    // Pepper specifies dimensions in DIPs (device-independent pixels). To
+    // generate a context that is at device-pixel resolution on HiDPI devices,
+    // scale the dimensions by view.GetDeviceScale().
+    int32_t new_width = view.GetRect().width() * view.GetDeviceScale();
+    int32_t new_height = view.GetRect().height() * view.GetDeviceScale();
 
     if (context_.is_null()) {
       if (!InitGL(new_width, new_height)) {