mus: Implement ScreenMus::GetCursorScreenPoint().

ui/views/mus/screen_mus.cc

 // Copyright 2016 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/views/mus/screen_mus.h"
 
 #include "mojo/converters/geometry/geometry_type_converters.h"
 #include "services/shell/public/cpp/connection.h"
 #include "services/shell/public/cpp/connector.h"
 #include "ui/gfx/display_finder.h"
@@ skipping 62 matching lines @@
   }
 };
 
 }  // namespace mojo
 
 namespace views {
 
 ScreenMus::ScreenMus(ScreenMusDelegate* delegate)
     : delegate_(delegate),
       primary_display_index_(0),
-      display_manager_observer_binding_(this) {}
+      display_manager_observer_binding_(this) {
+}
 
 ScreenMus::~ScreenMus() {}
 
 void ScreenMus::Init(shell::Connector* connector) {
   gfx::Screen::SetScreenInstance(this);
 
   connector->ConnectToInterface("mojo:mus", &display_manager_);
 
   display_manager_->AddObserver(
       display_manager_observer_binding_.CreateInterfacePtrAndBind());
@@ skipping 58 matching lines @@
       changed_display.device_scale_factor()) {
     local_display->set_device_scale_factor(
         changed_display.device_scale_factor());
     changed_values |= gfx::DisplayObserver::DISPLAY_METRIC_DEVICE_SCALE_FACTOR;
   }
   FOR_EACH_OBSERVER(gfx::DisplayObserver, observers_,
                     OnDisplayMetricsChanged(*local_display, changed_values));
 }
 
 gfx::Point ScreenMus::GetCursorScreenPoint() {
-  NOTIMPLEMENTED();
-  return gfx::Point();
+  if (!delegate_) {
+    // TODO(erg): If we need the cursor point in the window manager, we'll need
+    // to make |delegate_| required. It only recently changed to be optional.
+    NOTIMPLEMENTED();
+    return gfx::Point();
+  }
+  return delegate_->GetCursorScreenPoint();
 }
 
 gfx::NativeWindow ScreenMus::GetWindowUnderCursor() {
   NOTIMPLEMENTED();
   return nullptr;
 }
 
 gfx::NativeWindow ScreenMus::GetWindowAtScreenPoint(const gfx::Point& point) {
   NOTIMPLEMENTED();
   return nullptr;
@@ skipping 72 matching lines @@
   DCHECK_NE(-1, index);
   // Another display must become primary before the existing primary is
   // removed.
   DCHECK_NE(index, primary_display_index_);
   const gfx::Display display = displays_[index];
   FOR_EACH_OBSERVER(gfx::DisplayObserver, observers_,
                     OnDisplayRemoved(display));
 }
 
 }  // namespace views