Remove DisplayChangeObserver ash dependencies.

ui/display/chromeos/touchscreen_util_unittest.cc

 // Copyright 2014 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 "ui/display/chromeos/touchscreen_util.h"
 
 #include <memory>
 #include <string>
 #include <vector>
 
@@ skipping 12 matching lines @@
 class TouchscreenUtilTest : public testing::Test {
  public:
   TouchscreenUtilTest() {}
   ~TouchscreenUtilTest() override {}
 
   DisplayManager* display_manager() { return display_manager_.get(); }
 
   // testing::Test:
   void SetUp() override {
     // Recreate for each test, DisplayManager has a lot of state.
-    display_manager_ =
-        base::MakeUnique<DisplayManager>(base::MakeUnique<ScreenBase>());
+    display_manager_ = base::MakeUnique<DisplayManager>(
+        base::MakeUnique<ScreenBase>(), nullptr);
 
     // Internal display will always match to internal touchscreen. If internal
     // touchscreen can't be detected, it is then associated to a touch screen
     // with matching size.
     {
       ManagedDisplayInfo display(1, "1", false);
       scoped_refptr<ManagedDisplayMode> mode(new ManagedDisplayMode(
           gfx::Size(1920, 1080), 60.0, false /* interlaced */,
           true /* native */, 1.0 /* ui_scale */,
           1.0 /* device_scale_factor */));
@@ skipping 238 matching lines @@
   AssociateTouchscreens(&displays_, devices);
 
   EXPECT_EQ(1u, displays_[0].input_devices().size());
   EXPECT_EQ(1, displays_[0].input_devices()[0]);
   EXPECT_EQ(0u, displays_[1].input_devices().size());
   EXPECT_EQ(0u, displays_[2].input_devices().size());
   EXPECT_EQ(0u, displays_[3].input_devices().size());
 }
 
 }  // namespace display