Make always-on-top windows free-floating in Ash maximize mode

Currently windows in maximize mode are forced to be
maximized/centered, non-draggable, and non-resizable.
Applying these properties for always-on-top windows
leads to occlusion of content in other windows and thus
gives a poor user experience. This CL changes the behaviour
of MaximizeModeWindowManager to never manage windows
with the always-on-top property. As a result, any such
windows will be free-floating like in regular Ash.

BUG=458141
TEST=MaximizeModeWindowManagerTest.AlwaysOnTopWindows

Review URL: https://codereview.chromium.org/1063613003

Cr-Commit-Position: refs/heads/master@{#325749}

3 files changed, 91 insertions, 1 deletions

diff --git a/ash/wm/maximize_mode/maximize_mode_window_manager.cc b/ash/wm/maximize_mode/maximize_mode_window_manager.cc
index e4c91f7..28a71d0 100644
--- a/ash/wm/maximize_mode/maximize_mode_window_manager.cc
+++ b/ash/wm/maximize_mode/maximize_mode_window_manager.cc
@@ -17,6 +17,7 @@
 #include "ash/wm/wm_event.h"
 #include "ash/wm/workspace_controller.h"
 #include "base/command_line.h"
+#include "ui/aura/client/aura_constants.h"
 #include "ui/aura/window.h"
 #include "ui/gfx/screen.h"
 
@@ -122,6 +123,16 @@ void MaximizeModeWindowManager::OnWindowAdded(aura::Window* window) {
   }
 }
 
+void MaximizeModeWindowManager::OnWindowPropertyChanged(aura::Window* window,
+                                                        const void* key,
+                                                        intptr_t old) {
+  // Stop managing |window| if the always-on-top property is added.
+  if (key == aura::client::kAlwaysOnTopKey &&
+      window->GetProperty(aura::client::kAlwaysOnTopKey)) {
+    ForgetWindow(window);
+  }
+}
+
 void MaximizeModeWindowManager::OnWindowBoundsChanged(
     aura::Window* window,
     const gfx::Rect& old_bounds,
@@ -236,13 +247,19 @@ void MaximizeModeWindowManager::ForgetWindow(aura::Window* window) {
   window->RemoveObserver(this);
 
   // By telling the state object to revert, it will switch back the old
-  // State object and destroy itself, calling WindowStateDerstroyed().
+  // State object and destroy itself, calling WindowStateDestroyed().
   it->second->LeaveMaximizeMode(wm::GetWindowState(it->first));
   DCHECK(window_state_map_.find(window) == window_state_map_.end());
 }
 
 bool MaximizeModeWindowManager::ShouldHandleWindow(aura::Window* window) {
   DCHECK(window);
+
+  // Windows with the always-on-top property should be free-floating and thus
+  // not managed by us.
+  if (window->GetProperty(aura::client::kAlwaysOnTopKey))
+    return false;
+
   return window->type() == ui::wm::WINDOW_TYPE_NORMAL;
 }
 
diff --git a/ash/wm/maximize_mode/maximize_mode_window_manager.h b/ash/wm/maximize_mode/maximize_mode_window_manager.h
index b29bd6d..be64c6d 100644
--- a/ash/wm/maximize_mode/maximize_mode_window_manager.h
+++ b/ash/wm/maximize_mode/maximize_mode_window_manager.h
@@ -58,6 +58,9 @@ class ASH_EXPORT MaximizeModeWindowManager : public aura::WindowObserver,
   // Overridden from WindowObserver:
   void OnWindowDestroying(aura::Window* window) override;
   void OnWindowAdded(aura::Window* window) override;
+  void OnWindowPropertyChanged(aura::Window* window,
+                               const void* key,
+                               intptr_t old) override;
   void OnWindowBoundsChanged(aura::Window* window,
                              const gfx::Rect& old_bounds,
                              const gfx::Rect& new_bounds) override;
diff --git a/ash/wm/maximize_mode/maximize_mode_window_manager_unittest.cc b/ash/wm/maximize_mode/maximize_mode_window_manager_unittest.cc
index a57fa75..8011efe 100644
--- a/ash/wm/maximize_mode/maximize_mode_window_manager_unittest.cc
+++ b/ash/wm/maximize_mode/maximize_mode_window_manager_unittest.cc
@@ -1297,6 +1297,76 @@ TEST_F(MaximizeModeWindowManagerTest,
   DestroyMaximizeModeWindowManager();
 }
 
+// Tests that windows with the always-on-top property are not managed by
+// the MaximizeModeWindowManager while maximize mode is engaged (i.e.,
+// they remain free-floating).
+TEST_F(MaximizeModeWindowManagerTest, AlwaysOnTopWindows) {
+  gfx::Rect rect1(10, 10, 200, 50);
+  gfx::Rect rect2(20, 140, 100, 100);
+
+  // Create two windows with the always-on-top property.
+  scoped_ptr<aura::Window> w1(CreateWindow(ui::wm::WINDOW_TYPE_NORMAL, rect1));
+  scoped_ptr<aura::Window> w2(
+      CreateFixedSizeNonMaximizableWindow(ui::wm::WINDOW_TYPE_NORMAL, rect2));
+  w1->SetProperty(aura::client::kAlwaysOnTopKey, true);
+  w2->SetProperty(aura::client::kAlwaysOnTopKey, true);
+  EXPECT_FALSE(wm::GetWindowState(w1.get())->IsMaximized());
+  EXPECT_FALSE(wm::GetWindowState(w2.get())->IsMaximized());
+  EXPECT_EQ(rect1.ToString(), w1->bounds().ToString());
+  EXPECT_EQ(rect2.ToString(), w2->bounds().ToString());
+  EXPECT_TRUE(wm::GetWindowState(w1.get())->can_be_dragged());
+  EXPECT_TRUE(wm::GetWindowState(w2.get())->can_be_dragged());
+
+  // Enter maximize mode. Neither window should be managed because they have
+  // the always-on-top property set, which means that none of their properties
+  // should change.
+  ash::MaximizeModeWindowManager* manager = CreateMaximizeModeWindowManager();
+  ASSERT_TRUE(manager);
+  EXPECT_EQ(0, manager->GetNumberOfManagedWindows());
+  EXPECT_FALSE(wm::GetWindowState(w1.get())->IsMaximized());
+  EXPECT_FALSE(wm::GetWindowState(w2.get())->IsMaximized());
+  EXPECT_EQ(rect1.ToString(), w1->bounds().ToString());
+  EXPECT_EQ(rect2.ToString(), w2->bounds().ToString());
+  EXPECT_TRUE(wm::GetWindowState(w1.get())->can_be_dragged());
+  EXPECT_TRUE(wm::GetWindowState(w2.get())->can_be_dragged());
+
+  // Remove the always-on-top property from both windows while in maximize
+  // mode. The windows should become managed, which means they should be
+  // maximized/centered and no longer be draggable.
+  w1->SetProperty(aura::client::kAlwaysOnTopKey, false);
+  w2->SetProperty(aura::client::kAlwaysOnTopKey, false);
+  EXPECT_EQ(2, manager->GetNumberOfManagedWindows());
+  EXPECT_TRUE(wm::GetWindowState(w1.get())->IsMaximized());
+  EXPECT_FALSE(wm::GetWindowState(w2.get())->IsMaximized());
+  EXPECT_NE(rect1.origin().ToString(), w1->bounds().origin().ToString());
+  EXPECT_NE(rect1.size().ToString(), w1->bounds().size().ToString());
+  EXPECT_NE(rect2.origin().ToString(), w2->bounds().origin().ToString());
+  EXPECT_EQ(rect2.size().ToString(), w2->bounds().size().ToString());
+  EXPECT_FALSE(wm::GetWindowState(w1.get())->can_be_dragged());
+  EXPECT_FALSE(wm::GetWindowState(w2.get())->can_be_dragged());
+
+  // Applying the always-on-top property to both windows while in maximize
+  // mode should cause both windows to return to their original size,
+  // position, and state.
+  w1->SetProperty(aura::client::kAlwaysOnTopKey, true);
+  w2->SetProperty(aura::client::kAlwaysOnTopKey, true);
+  EXPECT_EQ(0, manager->GetNumberOfManagedWindows());
+  EXPECT_FALSE(wm::GetWindowState(w1.get())->IsMaximized());
+  EXPECT_FALSE(wm::GetWindowState(w2.get())->IsMaximized());
+  EXPECT_EQ(rect1.ToString(), w1->bounds().ToString());
+  EXPECT_EQ(rect2.ToString(), w2->bounds().ToString());
+  EXPECT_TRUE(wm::GetWindowState(w1.get())->can_be_dragged());
+  EXPECT_TRUE(wm::GetWindowState(w2.get())->can_be_dragged());
+
+  // The always-on-top windows should not change when leaving maximize mode.
+  DestroyMaximizeModeWindowManager();
+  EXPECT_FALSE(wm::GetWindowState(w1.get())->IsMaximized());
+  EXPECT_FALSE(wm::GetWindowState(w2.get())->IsMaximized());
+  EXPECT_EQ(rect1.ToString(), w1->bounds().ToString());
+  EXPECT_EQ(rect2.ToString(), w2->bounds().ToString());
+  EXPECT_TRUE(wm::GetWindowState(w1.get())->can_be_dragged());
+  EXPECT_TRUE(wm::GetWindowState(w2.get())->can_be_dragged());
+}
 #endif  // OS_WIN
 
 }  // namespace ash