[ash-md] Adds support for gesture to move selection in overview mode

ash/common/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/common/wm/overview/window_selector_controller.h"
 
 #include <vector>
 
 #include "ash/common/session/session_state_delegate.h"
 #include "ash/common/system/tray/system_tray_delegate.h"
@@ skipping 57 matching lines @@
     window_selector_->Init(windows);
     OnSelectionStarted();
   }
   return true;
 }
 
 bool WindowSelectorController::IsSelecting() const {
   return window_selector_.get() != NULL;
 }
 
+void WindowSelectorController::IncrementSelection(int increment) {
+  DCHECK(IsSelecting());
+  window_selector_->IncrementSelection(increment);
+}
+
+bool WindowSelectorController::AcceptSelection() {
+  DCHECK(IsSelecting());

[tdanderson, 2017/02/06 20:13:57]

Is this necessary given how you've documented AcceptSelection(), and given line
418 in window_selector.cc?

[varkha, 2017/02/08 20:41:13]

WindowSelectorController::IsSelecting is true when we are in overview mode, not
necessarily when a selection is made (selector widget present). So yes, it
confirms that we are in overview mode and can dereference window_selector_.
Maybe somewhat redundant but the crash won't happen immediately, it will happen
lower in stack and might be not obvious to grok, hence the DCHECK.

[tdanderson, 2017/02/08 23:14:19]

Acknowledged.

+  return window_selector_->AcceptSelection();
+}
+
 bool WindowSelectorController::IsRestoringMinimizedWindows() const {
   return window_selector_.get() != NULL &&
          window_selector_->restoring_minimized_windows();
 }
 
 // TODO(flackr): Make WindowSelectorController observe the activation of
 // windows, so we can remove WindowSelectorDelegate.
 void WindowSelectorController::OnSelectionEnded() {
   window_selector_->Shutdown();
   window_selector_.reset();
@@ skipping 27 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