CrOS Tablet Window management - Split Screen part I

ash/wm/overview/window_selector_controller.cc

 // Copyright 2013 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 "ash/wm/overview/window_selector_controller.h"
 
 #include <vector>
 
 #include "ash/session/session_controller.h"
 #include "ash/shell.h"
 #include "ash/shell_port.h"
 #include "ash/wm/mru_window_tracker.h"
 #include "ash/wm/overview/window_selector.h"
 #include "ash/wm/screen_pinning_controller.h"
+#include "ash/wm/splitview/split_view_controller.h"
 #include "ash/wm/window_state.h"
 #include "base/metrics/histogram_macros.h"
 
 namespace ash {
 
 WindowSelectorController::WindowSelectorController() {}
 
 WindowSelectorController::~WindowSelectorController() {
   // Destroy widgets that may be still animating if shell shuts down soon after
   // exiting overview mode.
@@ skipping 22 matching lines @@
     // Don't start overview if window selection is not allowed.
     if (!CanSelect())
       return false;
 
     auto windows = Shell::Get()->mru_window_tracker()->BuildMruWindowList();
     auto end =
         std::remove_if(windows.begin(), windows.end(),
                        std::not1(std::ptr_fun(&WindowSelector::IsSelectable)));
     windows.resize(end - windows.begin());
 
-    // Don't enter overview mode with no windows.
-    if (windows.empty())
-      return false;
+    if (!Shell::Get()->IsSplitViewModeActive()) {
+      // Don't enter overview with no window if the split view mode is inactive.
+      if (windows.empty())
+        return false;
+    } else {
+      // Don't enter overview with less than 1 window if the split view mode is
+      // active.
+      if (windows.size() <= 1)
+        return false;
+
+      // Remove the default snapped window from the window list. The default
+      // snapped window occupy one side of the screen, while the other windows
+      // occupy the other side of the screen in overview mode. The default snap
+      // position is the position where the window was firstly snapped. See
+      // |default_snap_position_| in SplitViewController for more detail.
+      aura::Window* default_snapped_window =
+          Shell::Get()->split_view_controller()->GetDefaultSnappedWindow();
+      auto iter =
+          std::find(windows.begin(), windows.end(), default_snapped_window);
+      DCHECK(iter != windows.end());
+      windows.erase(iter);
+    }
 
     Shell::Get()->NotifyOverviewModeStarting();
     window_selector_.reset(new WindowSelector(this));
     window_selector_->Init(windows);
     OnSelectionStarted();
   }
   return true;
 }
 
 bool WindowSelectorController::IsSelecting() const {
@@ skipping 50 matching lines @@
 }
 
 void WindowSelectorController::OnSelectionStarted() {
   if (!last_selection_time_.is_null()) {
     UMA_HISTOGRAM_LONG_TIMES("Ash.WindowSelector.TimeBetweenUse",
                              base::Time::Now() - last_selection_time_);
   }
 }
 
 }  // namespace ash