Enable CursorManager::LockCursor to lock cursor visibility.

ash/extended_desktop_unittest.cc

Index: ash/extended_desktop_unittest.cc
diff --git a/ash/extended_desktop_unittest.cc b/ash/extended_desktop_unittest.cc
index 5f4dd6c52d5e8a9f11c1c159cf679871899d48a7..db52a3c55c1798e16af9dfee7448dc47129f7f34 100644
--- a/ash/extended_desktop_unittest.cc
+++ b/ash/extended_desktop_unittest.cc
@@ -168,14 +168,7 @@ TEST_F(ExtendedDesktopTest, SystemModal) {
 
 TEST_F(ExtendedDesktopTest, TestCursor) {
   UpdateDisplay("1000x600,600x400");
-  Shell::GetInstance()->cursor_manager()->ShowCursor(false);
   Shell::RootWindowList root_windows = Shell::GetAllRootWindows();
-  EXPECT_FALSE(root_windows[0]->cursor_shown());
-  EXPECT_FALSE(root_windows[1]->cursor_shown());
-  Shell::GetInstance()->cursor_manager()->ShowCursor(true);
-  EXPECT_TRUE(root_windows[0]->cursor_shown());
-  EXPECT_TRUE(root_windows[1]->cursor_shown());
-
   EXPECT_EQ(ui::kCursorPointer, root_windows[0]->last_cursor().native_type());
   EXPECT_EQ(ui::kCursorPointer, root_windows[1]->last_cursor().native_type());
   Shell::GetInstance()->cursor_manager()->SetCursor(ui::kCursorCopy);