Keep the split view activities topmost in z-order in Athena

BUG=409888
TEST=WindowManagerTest.* SplitViewController.*

Review URL: https://codereview.chromium.org/550043002

Cr-Commit-Position: refs/heads/master@{#294665}

athena/athena.gyp

@@ -117,6 +117,7 @@
         'wm/window_list_provider_impl.cc',
         'wm/window_list_provider_impl.h',
         'wm/window_manager_impl.cc',
+        'wm/window_manager_impl.h',
         'wm/window_overview_mode.cc',
         'wm/window_overview_mode.h',
       ],

athena/wm/split_view_controller.cc

@@ -95,18 +95,8 @@ void SplitViewController::ActivateSplitMode(aura::Window* left,
   }
 
   SetState(ACTIVE);
-  if (right_window_ != right) {
-    right_window_ = right;
-    // Since the |window_list_provider_| controls directly the order of windows,
-    // it needs to change the window order accordingly.
-    window_list_provider_->MoveToFront(right_window_);
-  }
-  if (left_window_ != left) {
-    left_window_ = left;
-    // Since the |window_list_provider_| controls directly the order of windows,
-    // it needs to change the window order accordingly.
-    window_list_provider_->MoveToFront(left_window_);
-  }
+  right_window_ = right;
+  left_window_ = left;
   UpdateLayout(true);
 }
 
@@ -179,6 +169,9 @@ void SplitViewController::UpdateLayout(bool animate) {
 
   left_window_->Show();
   right_window_->Show();
+  window_list_provider_->MoveToFront(right_window_);
+  window_list_provider_->MoveToFront(left_window_);
+
   if (state_ == ACTIVE) {
     if (animate) {
       gfx::Transform left_transform = GetTargetTransformForBoundsAnimation(

athena/wm/split_view_controller_unittest.cc

@@ -32,6 +32,20 @@ class SplitViewControllerTest : public test::AthenaTestBase {
     test::AthenaTestBase::TearDown();
   }
 
+  // Returns whether the split view windows are topmost.
+  bool SplitViewWindowsTopmost() const {
+    SplitViewController* controller = api_->GetSplitViewController();
+    DCHECK(controller->IsSplitViewModeActive());
+    aura::Window::Windows list =
+        api_->GetWindowListProvider()->GetWindowList();
+    aura::Window* topmost = *list.rbegin();
+    aura::Window* second_topmost = *(list.rbegin() + 1);
+    return (topmost == controller->left_window() ||
+            topmost == controller->right_window()) &&
+           (second_topmost == controller->left_window() ||
+            second_topmost == controller->right_window());
+  }
+
   bool IsSplitViewAllowed() const {
     return api_->GetSplitViewController()->CanScroll();
   }
@@ -58,7 +72,6 @@ TEST_F(SplitViewControllerTest, SplitModeActivation) {
   }
 
   SplitViewController* controller = api()->GetSplitViewController();
-  WindowListProvider* list_provider = api()->GetWindowListProvider();
   ASSERT_FALSE(controller->IsSplitViewModeActive());
 
   controller->ActivateSplitMode(NULL, NULL);
@@ -66,34 +79,41 @@ TEST_F(SplitViewControllerTest, SplitModeActivation) {
   // The last two windows should be on the left and right, respectively.
   EXPECT_EQ(windows[kNumWindows - 1], controller->left_window());
   EXPECT_EQ(windows[kNumWindows - 2], controller->right_window());
+  EXPECT_TRUE(SplitViewWindowsTopmost());
 
   // Select the window that is currently on the left for the right panel. The
   // windows should switch.
   controller->ActivateSplitMode(NULL, windows[kNumWindows - 1]);
   EXPECT_EQ(windows[kNumWindows - 2], controller->left_window());
   EXPECT_EQ(windows[kNumWindows - 1], controller->right_window());
+  EXPECT_TRUE(SplitViewWindowsTopmost());
 
   controller->ActivateSplitMode(windows[kNumWindows - 1], NULL);
   EXPECT_EQ(windows[kNumWindows - 1], controller->left_window());
   EXPECT_EQ(windows[kNumWindows - 2], controller->right_window());
+  EXPECT_TRUE(SplitViewWindowsTopmost());
 
   // Select one of the windows behind the stacks for the right panel. The window
   // on the left should remain unchanged.
   controller->ActivateSplitMode(NULL, windows[0]);
   EXPECT_EQ(windows[kNumWindows - 1], controller->left_window());
   EXPECT_EQ(windows[0], controller->right_window());
-  EXPECT_EQ(windows[0], *list_provider->GetWindowList().rbegin());
+  EXPECT_TRUE(SplitViewWindowsTopmost());
 
   controller->ActivateSplitMode(windows[1], NULL);
   EXPECT_EQ(windows[1], controller->left_window());
   EXPECT_EQ(windows[0], controller->right_window());
-  EXPECT_EQ(windows[1], *list_provider->GetWindowList().rbegin());
+  EXPECT_TRUE(SplitViewWindowsTopmost());
 
   controller->ActivateSplitMode(windows[4], windows[5]);
   EXPECT_EQ(windows[4], controller->left_window());
   EXPECT_EQ(windows[5], controller->right_window());
-  EXPECT_EQ(windows[4], *list_provider->GetWindowList().rbegin());
-  EXPECT_EQ(windows[5], *(list_provider->GetWindowList().rbegin() + 1));
+  EXPECT_TRUE(SplitViewWindowsTopmost());
+
+  controller->ActivateSplitMode(windows[0], NULL);
+  EXPECT_EQ(windows[0], controller->left_window());
+  EXPECT_EQ(windows[5], controller->right_window());
+  EXPECT_TRUE(SplitViewWindowsTopmost());
 }
 
 TEST_F(SplitViewControllerTest, LandscapeOnly) {

athena/wm/window_manager_unittest.cc

@@ -260,8 +260,7 @@ TEST_F(WindowManagerTest, TitleDragSwitchBetweenWindowsInSplitViewMode) {
       wm_api.GetWindowListProvider()->GetWindowList();
   ASSERT_EQ(4u, windows.size());
   EXPECT_EQ(second.get(), windows[3]);
-  EXPECT_EQ(third.get(), windows[2]);
-  EXPECT_EQ(fourth.get(), windows[1]);
+  EXPECT_EQ(fourth.get(), windows[2]);
 
   // Swipe the title of the right window now. It should switch to |third|.
   generator.GestureScrollSequence(gfx::Point(x_middle + 20, 10),
@@ -270,6 +269,10 @@ TEST_F(WindowManagerTest, TitleDragSwitchBetweenWindowsInSplitViewMode) {
                                   5);
   EXPECT_EQ(second.get(), wm_api.GetSplitViewController()->left_window());
   EXPECT_EQ(third.get(), wm_api.GetSplitViewController()->right_window());
+  windows = wm_api.GetWindowListProvider()->GetWindowList();
+  ASSERT_EQ(4u, windows.size());
+  EXPECT_EQ(second.get(), windows[3]);
+  EXPECT_EQ(third.get(), windows[2]);
 }
 
 TEST_F(WindowManagerTest, NewWindowBounds) {