display: Fix DisplayList::UpdateDisplay losing pixel sizes

Updating displays in TestScreen loses the pixel size, which causes later
calls to SetDisplayRotation to revert updates of the display size made by
TestScreen::OnWindowBoundsChanged.

Bug: 1019015

Change-Id: I47d77665102c9500609cfd203740e320ef841af7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1889295
Commit-Queue: Michael Spang <spang@chromium.org>
Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#711138}

ui/display/display.h

@@ -193,9 +193,7 @@ class DISPLAY_EXPORT Display final {
 
   // Returns the display's size in pixel coordinates.
   gfx::Size GetSizeInPixel() const;
-#if defined(OS_ANDROID)
   void set_size_in_pixels(const gfx::Size& size) { size_in_pixels_ = size; }
-#endif  // defined(OS_ANDROID)
 
   // Returns a string representation of the display;
   std::string ToString() const;

ui/display/display_list.cc

@@ -104,6 +104,9 @@ uint32_t DisplayList::UpdateDisplay(const Display& display, Type type) {
     local_display->set_color_depth(color_depth);
     changed_values |= DisplayObserver::DISPLAY_METRIC_COLOR_SPACE;
   }
+  if (local_display->GetSizeInPixel() != display.GetSizeInPixel()) {
+    local_display->set_size_in_pixels(display.GetSizeInPixel());
+  }
   if (should_notify_observers()) {
     for (DisplayObserver& observer : observers_)
       observer.OnDisplayMetricsChanged(*local_display, changed_values);