chromeos: makes changes to can activate go to server

This is necessary as it's not uncommon to have code like this:

  SetCanActivate(true);
  widget->Activate();
  SetCanActivate(false);

BUG=928939
TEST=none

Change-Id: I52c2d79cd7aec2fe5ab13f8ae7821227f1a0214e
Reviewed-on: https://chromium-review.googlesource.com/c/1457117
Commit-Queue: Scott Violet <sky@chromium.org>
Reviewed-by: Michael Wasserman <msw@chromium.org>
Cr-Commit-Position: refs/heads/master@{#629866}

ui/aura/test/mus/test_window_tree.cc

@@ -332,7 +332,10 @@ void TestWindowTree::SetFocus(uint32_t change_id, ws::Id window_id) {
   OnChangeReceived(change_id, WindowTreeChangeType::FOCUS);
 }
 
-void TestWindowTree::SetCanFocus(ws::Id window_id, bool can_focus) {}
+void TestWindowTree::SetCanFocus(ws::Id window_id, bool can_focus) {
+  ++can_focus_count_;
+  last_can_focus_ = can_focus;
+}
 
 void TestWindowTree::SetEventTargetingPolicy(
     ws::Id window_id,

ui/aura/test/mus/test_window_tree.h

@@ -146,6 +146,13 @@ class TestWindowTree : public ws::mojom::WindowTree {
     return value;
   }
 
+  bool last_can_focus() const { return last_can_focus_; }
+  size_t get_and_clear_can_focus_count() {
+    const int value = can_focus_count_;
+    can_focus_count_ = 0u;
+    return value;
+  }
+
   int last_move_hit_test() const { return last_move_hit_test_; }
 
   size_t get_and_clear_window_resize_shadow_count() {
@@ -336,6 +343,8 @@ class TestWindowTree : public ws::mojom::WindowTree {
   ws::Id last_transfer_new_ = 0u;
   bool last_transfer_should_cancel_ = false;
   bool last_accepts_drops_ = false;
+  size_t can_focus_count_ = 0u;
+  bool last_can_focus_ = false;
 
   size_t accepts_drops_count_ = 0u;
 

ui/views/mus/desktop_window_tree_host_mus.cc

@@ -935,7 +935,8 @@ void DesktopWindowTreeHostMus::SetBoundsInDIP(const gfx::Rect& bounds_in_dip) {
 }
 
 void DesktopWindowTreeHostMus::OnCanActivateChanged() {
-  // TODO(crbug.com/928939): call to WindowTreeClient::SetCanFocus()
+  MusClient::Get()->window_tree_client()->SetCanFocus(
+      window(), native_widget_delegate_->CanActivate());
 }
 
 void DesktopWindowTreeHostMus::OnWindowManagerFrameValuesChanged() {

ui/views/mus/desktop_window_tree_host_mus_unittest.cc

@@ -1075,6 +1075,30 @@ TEST_F(DesktopWindowTreeHostMusTest, MinMaxSize) {
   EXPECT_FALSE(window->GetProperty(aura::client::kMaximumSize));
 }
 
+TEST_F(DesktopWindowTreeHostMusTest, SetCanFocus) {
+  auto* delegate = new WidgetDelegateView;
+  std::unique_ptr<Widget> widget = CreateWidget(delegate);
+  // Swap the WindowTree implementation to verify SetCanFocus() is called when
+  // the active state changes.
+  aura::TestWindowTree test_window_tree;
+  aura::WindowTreeClientTestApi window_tree_client_private(
+      MusClient::Get()->window_tree_client());
+  ws::mojom::WindowTree* old_tree =
+      window_tree_client_private.SwapTree(&test_window_tree);
+
+  delegate->SetCanActivate(false);
+  EXPECT_FALSE(delegate->CanActivate());
+  EXPECT_FALSE(test_window_tree.last_can_focus());
+  EXPECT_EQ(1u, test_window_tree.get_and_clear_can_focus_count());
+
+  delegate->SetCanActivate(true);
+  EXPECT_TRUE(delegate->CanActivate());
+  EXPECT_TRUE(test_window_tree.last_can_focus());
+  EXPECT_EQ(1u, test_window_tree.get_and_clear_can_focus_count());
+
+  window_tree_client_private.SwapTree(old_tree);
+}
+
 // DesktopWindowTreeHostMusTest with --force-device-scale-factor=1.25.
 class DesktopWindowTreeHostMusTestFractionalDPI
     : public DesktopWindowTreeHostMusTest {