Hookup device dpi for ChromeOS

ash/display/display_change_observer_chromeos.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/display/display_change_observer_chromeos.h"
 
 #include <algorithm>
 #include <map>
 #include <set>
 #include <string>
@@ skipping 169 matching lines @@
   UpdateInternalDisplayId(display_states);
 
   std::vector<DisplayInfo> displays;
   std::set<int64> ids;
   for (const ui::DisplaySnapshot* state : display_states) {
     const ui::DisplayMode* mode_info = state->current_mode();
     if (!mode_info)
       continue;
 
     float device_scale_factor = 1.0f;
+    float dpi =
+        kInchInMm * mode_info->size().width() / state->physical_size().width();

[oshima, 2015/09/15 17:34:24]

can you check against black listed size and fallback to 96?

     if (state->type() == ui::DISPLAY_CONNECTION_TYPE_INTERNAL) {
-      if (!ui::IsDisplaySizeBlackListed(state->physical_size())) {
-        device_scale_factor =
-            FindDeviceScaleFactor((kInchInMm * mode_info->size().width() /
-                                   state->physical_size().width()));
-      }
+      if (!ui::IsDisplaySizeBlackListed(state->physical_size()))
+        device_scale_factor = FindDeviceScaleFactor(dpi);
     } else {
       DisplayMode mode;
       if (Shell::GetInstance()->display_manager()->GetSelectedModeForDisplayId(
               state->display_id(), &mode)) {
         device_scale_factor = mode.device_scale_factor;
       } else {
         // For monitors that are 40 inches and 4K or above, set
         // |device_scale_factor| to 2x. For margin purposes, 100 is subtracted
         // from the value of |k2xThreshouldSizeSquaredFor4KInMm|
         const int k2xThreshouldSizeSquaredFor4KInMm =
@@ skipping 21 matching lines @@
     int64 id = state->display_id();
     ids.insert(id);
 
     displays.push_back(DisplayInfo(id, name, has_overscan));
     DisplayInfo& new_info = displays.back();
     new_info.set_device_scale_factor(device_scale_factor);
     new_info.SetBounds(display_bounds);
     new_info.set_native(true);
     new_info.set_is_aspect_preserving_scaling(
         state->is_aspect_preserving_scaling());
+    new_info.set_device_dpi(dpi);
 
     std::vector<DisplayMode> display_modes =
         (state->type() == ui::DISPLAY_CONNECTION_TYPE_INTERNAL)
             ? GetInternalDisplayModeList(new_info, *state)
             : GetExternalDisplayModeList(*state);
     new_info.SetDisplayModes(display_modes);
 
     new_info.set_available_color_profiles(
         Shell::GetInstance()
             ->display_configurator()
@@ skipping 39 matching lines @@
   }
   return 1.0f;
 }
 
 void DisplayChangeObserver::OnTouchscreenDeviceConfigurationChanged() {
   OnDisplayModeChanged(
       Shell::GetInstance()->display_configurator()->cached_displays());
 }
 
 }  // namespace ash