athena: Fix switching windows with title-drag in split-view.

athena/wm/split_view_controller.cc

 // 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 "athena/wm/split_view_controller.h"
 
 #include <cmath>
 
 #include "athena/wm/public/window_list_provider.h"
 #include "athena/wm/public/window_manager.h"
@@ skipping 67 matching lines @@
     right_window_ = right;
     container_->StackChildAtTop(right_window_);
   }
   if (left_window_ != left) {
     left_window_ = left;
     container_->StackChildAtTop(left_window_);
   }
   UpdateLayout(true);
 }
 
+void SplitViewController::ReplaceWindow(aura::Window* window,
+                                        aura::Window* replace_with) {
+  CHECK(IsSplitViewModeActive());
+  CHECK(replace_with);
+  CHECK(window == left_window_ || window == right_window_);
+  CHECK(replace_with != left_window_ && replace_with != right_window_);
+#if !defined(NDEBUG)
+  aura::Window::Windows windows = window_list_provider_->GetWindowList();
+  DCHECK(std::find(windows.begin(), windows.end(), replace_with) !=
+         windows.end());
+#endif
+
+  replace_with->SetBounds(window->bounds());
+  replace_with->SetTransform(gfx::Transform());
+  if (window == left_window_)
+    left_window_ = replace_with;
+  else
+    right_window_ = replace_with;
+  wm::ActivateWindow(replace_with);
+  window->SetTransform(gfx::Transform());
+}
+
 void SplitViewController::DeactivateSplitMode() {
   CHECK_NE(SCROLLING, state_);
   state_ = INACTIVE;
   left_window_ = right_window_ = NULL;
 }
 
 void SplitViewController::UpdateLayout(bool animate) {
   if  (!left_window_)
     return;
   CHECK(right_window_);
@@ skipping 144 matching lines @@
 }
 
 bool SplitViewController::CanScroll() {
   // TODO(mfomitchev): return false in vertical orientation, in full screen.
   bool result = (!IsSplitViewModeActive() &&
                  window_list_provider_->GetWindowList().size() >= 2);
   return result;
 }
 
 }  // namespace athena