Support dragging panels to stack and snap.

chrome/browser/ui/panels/base_panel_browser_test.cc

Index: chrome/browser/ui/panels/base_panel_browser_test.cc
diff --git a/chrome/browser/ui/panels/base_panel_browser_test.cc b/chrome/browser/ui/panels/base_panel_browser_test.cc
index 440ee628c837e4d8a76f969d6c3a280942db8236..fb425997005fe61a716795f45db05facdbb29ac4 100644
--- a/chrome/browser/ui/panels/base_panel_browser_test.cc
+++ b/chrome/browser/ui/panels/base_panel_browser_test.cc
@@ -17,6 +17,7 @@
 #include "chrome/browser/ui/panels/native_panel.h"
 #include "chrome/browser/ui/panels/panel_collection.h"
 #include "chrome/browser/ui/panels/panel_mouse_watcher.h"
+#include "chrome/browser/ui/panels/stacked_panel_collection.h"
 #include "chrome/browser/ui/panels/test_panel_active_state_observer.h"
 #include "chrome/browser/ui/panels/test_panel_mouse_watcher.h"
 #include "chrome/common/chrome_notification_types.h"
@@ -390,6 +391,18 @@ Panel* BasePanelBrowserTest::CreateDetachedPanel(const std::string& name,
   return panel;
 }
 
+Panel* BasePanelBrowserTest::CreateStackedPanel(const std::string& name,
+                                                const gfx::Rect& bounds,
+                                                StackedPanelCollection* stack) {
+  Panel* panel = CreateDetachedPanel(name, bounds);
+  panel->manager()->MovePanelToCollection(panel,
+                                          stack,
+                                          PanelCollection::DEFAULT_POSITION);
+  EXPECT_EQ(PanelCollection::STACKED, panel->collection()->type());
+  WaitForBoundsAnimationFinished(panel);
+  return panel;
+}
+
 // static
 NativePanelTesting* BasePanelBrowserTest::CreateNativePanelTesting(
     Panel* panel) {