Fix shelf dimming on secondary display

ash/shelf/shelf_layout_manager_unittest.cc

Index: ash/shelf/shelf_layout_manager_unittest.cc
diff --git a/ash/shelf/shelf_layout_manager_unittest.cc b/ash/shelf/shelf_layout_manager_unittest.cc
index 1ad54a81bee5b5b926772c202a3d901ebc3ec6f7..7d84adc67dc73020b133be40db0f86fed4230df7 100644
--- a/ash/shelf/shelf_layout_manager_unittest.cc
+++ b/ash/shelf/shelf_layout_manager_unittest.cc
@@ -1118,7 +1118,7 @@ TEST_F(ShelfLayoutManagerTest, SetAutoHideBehavior) {
 }
 
 // Basic assertions around the dimming of the shelf.
-TEST_F(ShelfLayoutManagerTest, TestDimmingBehavior) {
+TEST_F(ShelfLayoutManagerTest, DimmingBehavior) {
   // Since ShelfLayoutManager queries for mouse location, move the mouse so
   // it isn't over the shelf.
   ui::test::EventGenerator generator(Shell::GetPrimaryRootWindow(),
@@ -1191,8 +1191,63 @@ TEST_F(ShelfLayoutManagerTest, TestDimmingBehavior) {
   EXPECT_EQ(-1, shelf->shelf_widget()->GetDimmingAlphaForTest());
 }
 
+// Test that dimming works correctly with multiple displays.
+TEST_F(ShelfLayoutManagerTest, DimmingBehaviorDualDisplay) {
+  if (!SupportsMultipleDisplays())
+    return;
+
+  // Create two displays.
+  Shell* shell = Shell::GetInstance();
+  UpdateDisplay("0+0-200x200,+200+0-100x100");
+  EXPECT_EQ(2U, shell->display_manager()->GetNumDisplays());
+
+  DisplayController* display_controller = shell->display_controller();
+  aura::Window::Windows root_windows = display_controller->GetAllRootWindows();
+  EXPECT_EQ(root_windows.size(), 2U);
+
+  std::vector<ShelfWidget*> shelf_widgets;
+  for (auto& root_window : root_windows) {
+    ShelfLayoutManager* shelf =
+        GetRootWindowController(root_window)->GetShelfLayoutManager();
+    shelf_widgets.push_back(shelf->shelf_widget());
+
+    // For disabling the dimming animation to work, the animation must be
+    // disabled prior to creating the dimmer.
+    shelf_widgets.back()->DisableDimmingAnimationsForTest();
+
+    // Create a maximized window to create the dimmer.
+    views::Widget* widget = new views::Widget;
+    views::Widget::InitParams params(views::Widget::InitParams::TYPE_WINDOW);
+    params.context = root_window;
+    params.bounds = root_window->GetBoundsInScreen();
+    params.show_state = ui::SHOW_STATE_MAXIMIZED;
+    widget->Init(params);
+    widget->Show();
+  }
+
+  ui::test::EventGenerator& generator(GetEventGenerator());
+
+  generator.MoveMouseTo(root_windows[0]->GetBoundsInScreen().CenterPoint());
+  EXPECT_LT(0, shelf_widgets[0]->GetDimmingAlphaForTest());
+  EXPECT_LT(0, shelf_widgets[1]->GetDimmingAlphaForTest());
+
+  generator.MoveMouseTo(
+      shelf_widgets[0]->GetWindowBoundsInScreen().CenterPoint());
+  EXPECT_EQ(0, shelf_widgets[0]->GetDimmingAlphaForTest());
+  EXPECT_LT(0, shelf_widgets[1]->GetDimmingAlphaForTest());
+
+  generator.MoveMouseTo(
+      shelf_widgets[1]->GetWindowBoundsInScreen().CenterPoint());
+  EXPECT_LT(0, shelf_widgets[0]->GetDimmingAlphaForTest());
+  EXPECT_EQ(0, shelf_widgets[1]->GetDimmingAlphaForTest());
+
+  generator.MoveMouseTo(root_windows[1]->GetBoundsInScreen().CenterPoint());
+  EXPECT_LT(0, shelf_widgets[0]->GetDimmingAlphaForTest());
+  EXPECT_LT(0, shelf_widgets[1]->GetDimmingAlphaForTest());
+}
+
 // Assertions around the dimming of the shelf in conjunction with menus.
-TEST_F(ShelfLayoutManagerTest, TestDimmingBehaviorWithMenus) {
+TEST_F(ShelfLayoutManagerTest, DimmingBehaviorWithMenus) {
   // Since ShelfLayoutManager queries for mouse location, move the mouse so
   // it isn't over the shelf.
   ui::test::EventGenerator generator(Shell::GetPrimaryRootWindow(),