Tab dragging as implemented as a mus API.

components/mus/public/cpp/lib/in_flight_change.cc

Index: components/mus/public/cpp/lib/in_flight_change.cc
diff --git a/components/mus/public/cpp/lib/in_flight_change.cc b/components/mus/public/cpp/lib/in_flight_change.cc
index 048787423502807135b607572b89e1f4a47d91d2..1d1bb47343e72d55386bf570e3bdb1b60c1fff77 100644
--- a/components/mus/public/cpp/lib/in_flight_change.cc
+++ b/components/mus/public/cpp/lib/in_flight_change.cc
@@ -39,6 +39,22 @@ void InFlightBoundsChange::Revert() {
   WindowPrivate(window()).LocalSetBounds(window()->bounds(), revert_bounds_);
 }
 
+// InFlightMoveLoopChange -----------------------------------------------------
+
+InFlightMoveLoopChange::InFlightMoveLoopChange(Window* window,
+                                               const gfx::Rect& revert_bounds)
+    : InFlightChange(window, ChangeType::MOVE_LOOP),
+      revert_bounds_(revert_bounds) {}
+
+void InFlightMoveLoopChange::SetRevertValueFrom(const InFlightChange& change) {
+  revert_bounds_ =
+      static_cast<const InFlightMoveLoopChange&>(change).revert_bounds_;
+}
+
+void InFlightMoveLoopChange::Revert() {
+  WindowPrivate(window()).LocalSetBounds(window()->bounds(), revert_bounds_);

[sky, 2016/06/22 23:47:56]

This is problematic because it may conflict with any InFlightBoundsChanges. For
example, consider the following scenario:
. start move loop
. Window::SetBounds (in client)
. move loop canceled

In this case you don't want to change the bounds at all.

I think you need to use an InFlightBoundsChange so revert values are properly
merged.

+}
+
 // CrashInFlightChange --------------------------------------------------------
 
 CrashInFlightChange::CrashInFlightChange(Window* window, ChangeType type)