Store rotation/ui scale to local state.

ash/display/display_info.cc

 // Copyright (c) 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 <stdio.h>
 #include <string>
 #include <vector>
 
 #include "ash/display/display_info.h"
 #include "base/logging.h"
@@ skipping 120 matching lines @@
 
 void DisplayInfo::CopyFromNative(const DisplayInfo& native_info) {
   DCHECK(id_ == native_info.id_);
   name_ = native_info.name_;
   has_overscan_ = native_info.has_overscan_;
 
   DCHECK(!native_info.bounds_in_pixel_.IsEmpty());
   bounds_in_pixel_ = native_info.bounds_in_pixel_;
   size_in_pixel_ = native_info.size_in_pixel_;
   device_scale_factor_ = native_info.device_scale_factor_;
-  rotation_ = native_info.rotation_;
-  ui_scale_ = native_info.ui_scale_;
+
+  // Rotation_ and ui_scale_ are given by preference, or unit
+  // tests. Don't copy if this native_info came from
+  // DisplayChangeObserverX11.
+  if (native_info.ui_scale() >= 1.0f) {
+    rotation_ = native_info.rotation_;
+    ui_scale_ = native_info.ui_scale_;
+  }
+  // It makes little sense to scale beyond the original
+  // resolution. This guard is to protect applying
+  // ui_scale to an external display whose DPI has changed
+  // from 2.0 to 1.0 for some reason.
+  if (ui_scale_ > device_scale_factor_)
+    ui_scale_ = 1.0f;
+
   // Don't copy insets as it may be given by preference.  |rotation_|
   // is treated as a native so that it can be specified in
   // |CreateFromSpec|.
 }
 
 void DisplayInfo::SetBounds(const gfx::Rect& new_bounds_in_pixel) {
   bounds_in_pixel_ = new_bounds_in_pixel;
   size_in_pixel_ = new_bounds_in_pixel.size();
   UpdateDisplaySize();
 }
@@ skipping 46 matching lines @@
       bounds_in_pixel_.ToString().c_str(),
       size_in_pixel_.ToString().c_str(),
       device_scale_factor_,
       overscan_insets_in_dip_.ToString().c_str(),
       rotation_degree,
       ui_scale_);
 }
 
 }  // namespace internal
 }  // namespace ash