Listen to Display reconfiguration and notify DisplayObservers on Mac.

ui/gfx/display_change_notifier.cc

Index: ui/gfx/display_change_notifier.cc
diff --git a/ui/gfx/display_change_notifier.cc b/ui/gfx/display_change_notifier.cc
new file mode 100644
index 0000000000000000000000000000000000000000..380c32ca9c3defa97f8c0992e815d88bf3256c5d
--- /dev/null
+++ b/ui/gfx/display_change_notifier.cc
@@ -0,0 +1,92 @@
+// 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/gfx/display_change_notifier.h"
+
+#include "ui/gfx/display.h"
+#include "ui/gfx/display_observer.h"
+
+namespace gfx {
+
+namespace {
+
+class DisplayComparator {
+ public:
+  explicit DisplayComparator(const Display& display)
+    : display_id_(display.id())
+  {}
+
+  bool operator()(const Display& display) const {
+    return display.id() == display_id_;
+  }
+
+ private:
+  int64 display_id_;
+};
+
+} // anonymous namespace
+
+DisplayChangeNotifier::DisplayChangeNotifier() {
+}
+
+DisplayChangeNotifier::~DisplayChangeNotifier() {
+}
+
+void DisplayChangeNotifier::AddObserver(DisplayObserver* obs) {
+  observer_list_.AddObserver(obs);
+}
+
+void DisplayChangeNotifier::RemoveObserver(DisplayObserver* obs) {
+  observer_list_.RemoveObserver(obs);
+}
+
+void DisplayChangeNotifier::NotifyDisplaysChanged(
+    const std::vector<Display>& old_displays,
+    const std::vector<Display>& new_displays) {
+  // Display present in old_displays but not in new_displays has been removed.
+  std::vector<Display>::const_iterator old_it = old_displays.begin();
+  for (; old_it != old_displays.end(); ++old_it) {
+    if (std::find_if(new_displays.begin(), new_displays.end(),
+                     DisplayComparator(*old_it)) == new_displays.end()) {
+      FOR_EACH_OBSERVER(DisplayObserver, observer_list_,
+                        OnDisplayRemoved(*old_it));
+    }
+  }
+
+  // Display present in new_displays but not in old_displays has been added.
+  // Display present in both might have been modified.
+  for (std::vector<Display>::const_iterator new_it =
+          new_displays.begin(); new_it != new_displays.end(); ++new_it) {
+    std::vector<Display>::const_iterator old_it = std::find_if(
+        old_displays.begin(), old_displays.end(), DisplayComparator(*new_it));
+
+    if (old_it == old_displays.end()) {
+      FOR_EACH_OBSERVER(DisplayObserver, observer_list_,
+                        OnDisplayAdded(*new_it));
+      continue;
+    }
+
+    uint32_t metrics = DisplayObserver::DISPLAY_METRIC_NONE;
+
+    if (new_it->bounds() != old_it->bounds())
+      metrics |= DisplayObserver::DISPLAY_METRIC_BOUNDS;
+
+    if (new_it->rotation() != old_it->rotation())
+      metrics |= DisplayObserver::DISPLAY_METRIC_ROTATION;
+
+    if (new_it->work_area() != old_it->work_area())
+      metrics |= DisplayObserver::DISPLAY_METRIC_WORK_AREA;
+
+    if (new_it->device_scale_factor() != old_it->device_scale_factor())
+      metrics |= DisplayObserver::DISPLAY_METRIC_DEVICE_SCALE_FACTOR;
+
+    if (metrics != DisplayObserver::DISPLAY_METRIC_NONE) {
+      FOR_EACH_OBSERVER(DisplayObserver,
+                        observer_list_,
+                        OnDisplayMetricsChanged(*new_it, metrics));
+    }
+  }
+}
+
+} // namespace gfx