Add observers for DIP scale change.

ui/android/BUILD.gn

 # Copyright 2015 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.
 
 import("//build/config/android/rules.gni")
 import("//testing/test.gni")
 
 assert(is_android)
 
 component("android") {
@@ skipping 143 matching lines @@
     "java/src/org/chromium/ui/UiUtils.java",
     "java/src/org/chromium/ui/VSyncMonitor.java",
     "java/src/org/chromium/ui/autofill/AutofillDelegate.java",
     "java/src/org/chromium/ui/autofill/AutofillKeyboardAccessory.java",
     "java/src/org/chromium/ui/autofill/AutofillPopup.java",
     "java/src/org/chromium/ui/autofill/AutofillSuggestion.java",
     "java/src/org/chromium/ui/base/ActivityWindowAndroid.java",
     "java/src/org/chromium/ui/base/AndroidPermissionDelegate.java",
     "java/src/org/chromium/ui/base/Clipboard.java",
     "java/src/org/chromium/ui/base/DeviceFormFactor.java",
+    "java/src/org/chromium/ui/base/DisplayObserver.java",
     "java/src/org/chromium/ui/base/LocalizationUtils.java",
     "java/src/org/chromium/ui/base/ResourceBundle.java",
     "java/src/org/chromium/ui/base/SelectFileDialog.java",
     "java/src/org/chromium/ui/base/TouchDevice.java",
     "java/src/org/chromium/ui/base/ViewAndroidDelegate.java",
     "java/src/org/chromium/ui/base/WindowAndroid.java",
     "java/src/org/chromium/ui/gfx/BitmapHelper.java",
     "java/src/org/chromium/ui/gfx/DeviceDisplayInfo.java",
+    "java/src/org/chromium/ui/gfx/DisplaySwitches.java",
     "java/src/org/chromium/ui/gfx/ViewConfigurationHelper.java",
     "java/src/org/chromium/ui/gl/SurfaceTextureListener.java",
     "java/src/org/chromium/ui/gl/SurfaceTexturePlatformWrapper.java",
     "java/src/org/chromium/ui/interpolators/BakedBezierInterpolator.java",
     "java/src/org/chromium/ui/picker/ChromeDatePickerDialog.java",
     "java/src/org/chromium/ui/picker/DateDialogNormalizer.java",
     "java/src/org/chromium/ui/picker/DateTimePickerDialog.java",
     "java/src/org/chromium/ui/picker/DateTimeSuggestion.java",
     "java/src/org/chromium/ui/picker/DateTimeSuggestionListAdapter.java",
     "java/src/org/chromium/ui/picker/InputDialogContainer.java",
@@ skipping 75 matching lines @@
     "//cc",
     "//cc:test_support",
     "//skia",
     "//testing/gmock",
     "//testing/gtest",
     "//ui/base",
     "//ui/gfx",
     "//ui/resources:ui_test_pak",
   ]
 }