Add more out of line copy ctors for complex classes.

components/mus/ws/test_change_tracker.cc

Index: components/mus/ws/test_change_tracker.cc
diff --git a/components/mus/ws/test_change_tracker.cc b/components/mus/ws/test_change_tracker.cc
index 8416f9594909de6203005b952b3b2a98d21d4d4a..aefa54e08c0376022f401fbad4a9dc1ae59aed5b 100644
--- a/components/mus/ws/test_change_tracker.cc
+++ b/components/mus/ws/test_change_tracker.cc
@@ -198,6 +198,8 @@ Change::Change()
       bool_value(false),
       change_id(0u) {}
 
+Change::Change(const Change& other) = default;
+
 Change::~Change() {}
 
 TestChangeTracker::TestChangeTracker() : delegate_(NULL) {}
@@ -391,6 +393,8 @@ void TestChangeTracker::AddChange(const Change& change) {
 
 TestWindow::TestWindow() {}
 
+TestWindow::TestWindow(const TestWindow& other) = default;
+
 TestWindow::~TestWindow() {}
 
 std::string TestWindow::ToString() const {