Fix moving the mouse between two displays after the secondary display becomes primary.

ash/display/extended_mouse_warp_controller.cc

 // Copyright 2015 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/display/extended_mouse_warp_controller.h"
 
 #include <cmath>
 
 #include "ash/display/display_manager.h"
 #include "ash/display/display_util.h"
@@ skipping 70 matching lines @@
   // horizontally, with each display being RIGHT of the previous one.
   if (display_manager->GetNumDisplays() > 2) {
     for (size_t i = 1; i < display_manager->GetNumDisplays(); ++i) {
       const gfx::Display& left = display_manager->GetDisplayAt(i - 1);
       const gfx::Display& right = display_manager->GetDisplayAt(i);
 
       AddWarpRegion(CreateVerticalEdgeBounds(left, right, DisplayLayout::RIGHT),
                     drag_source != nullptr);
     }
   } else {
+    // Make sure to set |a| as the primary display, and |b| as the secondary
+    // display. DisplayLayout::Position is defined in terms of primary.
     DisplayLayout::Position position =
         display_manager->GetCurrentDisplayLayout().position;
-    const gfx::Display& a = display_manager->GetDisplayAt(0);
-    const gfx::Display& b = display_manager->GetDisplayAt(1);
+    const gfx::Display& a = Shell::GetScreen()->GetPrimaryDisplay();
+    const gfx::Display& b = ScreenUtil::GetSecondaryDisplay();
 
     // TODO(oshima): Use ComputeBondary instead.
-    if (position == DisplayLayout::TOP || position == DisplayLayout::BOTTOM)
+    if (position == DisplayLayout::TOP || position == DisplayLayout::BOTTOM) {
       AddWarpRegion(CreateHorizontalEdgeBounds(a, b, position),
                     drag_source != nullptr);
-    else
+    } else {
       AddWarpRegion(CreateVerticalEdgeBounds(a, b, position),
                     drag_source != nullptr);
+    }
   }
 }
 
 ExtendedMouseWarpController::~ExtendedMouseWarpController() {
 }
 
 bool ExtendedMouseWarpController::WarpMouseCursor(ui::MouseEvent* event) {
   if (Shell::GetScreen()->GetNumDisplays() <= 1 || !enabled_)
     return false;
 
@@ skipping 28 matching lines @@
 
   return WarpMouseCursorInNativeCoords(point_in_native, point_in_screen, false);
 }
 
 void ExtendedMouseWarpController::SetEnabled(bool enabled) {
   enabled_ = enabled;
 }
 
 void ExtendedMouseWarpController::AddWarpRegion(
     scoped_ptr<WarpRegion> warp_region,
-    bool drag_source) {
-  if (drag_source) {
+    bool has_drag_source) {
+  if (has_drag_source) {
     warp_region->shared_display_edge_indicator.reset(
         new SharedDisplayEdgeIndicator);
     warp_region->shared_display_edge_indicator->Show(
         warp_region->a_indicator_bounds, warp_region->b_indicator_bounds);
   }
 
   warp_regions_.emplace_back(std::move(warp_region));
 }
 
 bool ExtendedMouseWarpController::WarpMouseCursorInNativeCoords(
@@ skipping 102 matching lines @@
     upper_indicator_y = std::max(upper_indicator_y, upper_shared_y);
   }
   a_indicator_bounds.set_y(upper_indicator_y);
   a_indicator_bounds.set_height(lower_indicator_y - upper_indicator_y);
 
   return make_scoped_ptr(
       new WarpRegion(a.id(), b.id(), a_indicator_bounds, b_indicator_bounds));
 }
 
 }  // namespace ash