[Chromecast] Add support for z-order and window focus.

chromecast/graphics/cast_window_manager_aura.cc

 // Copyright 2017 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 "chromecast/graphics/cast_window_manager_aura.h"
 
 #include "base/memory/ptr_util.h"
 #include "ui/aura/client/default_capture_client.h"
+#include "ui/aura/client/focus_change_observer.h"
 #include "ui/aura/env.h"
 #include "ui/aura/layout_manager.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_tree_host_platform.h"
 #include "ui/base/ime/input_method.h"
 #include "ui/base/ime/input_method_factory.h"
 #include "ui/display/display.h"
 #include "ui/display/screen.h"
 
 namespace chromecast {
@@ skipping 110 matching lines @@
   CHECK(aura::Env::GetInstance());
   window_tree_host_.reset(
       new CastWindowTreeHost(enable_input_, gfx::Rect(display_size)));
   window_tree_host_->InitHost();
   window_tree_host_->window()->SetLayoutManager(new CastLayoutManager());
 
   // Allow seeing through to the hardware video plane:
   window_tree_host_->compositor()->SetHostHasTransparentBackground(true);
   window_tree_host_->compositor()->SetBackgroundColor(SK_ColorTRANSPARENT);
 
+  aura::client::SetFocusClient(window_tree_host_->window(), &focus_client_);
   capture_client_.reset(
       new aura::client::DefaultCaptureClient(window_tree_host_->window()));
 
   CastVSyncSettings::GetInstance()->AddObserver(this);
   window_tree_host_->compositor()->SetAuthoritativeVSyncInterval(
       CastVSyncSettings::GetInstance()->GetVSyncInterval());
 
   window_tree_host_->Show();
 }
 
 void CastWindowManagerAura::TearDown() {
   if (!window_tree_host_) {
     return;
   }
+  focus_client_.reset();

[halliwell, 2017/01/24 00:54:46]

Can you explain why you needed this?

[Joshua LeVasseur, 2017/01/24 03:39:50]

I've switched to using a smart pointer, so that should make it clearer (ensure
that we discard state).

   CastVSyncSettings::GetInstance()->RemoveObserver(this);
   capture_client_.reset();
+  aura::client::SetFocusClient(window_tree_host_->window(), nullptr);
   window_tree_host_.reset();
 }
 
 void CastWindowManagerAura::AddWindow(gfx::NativeView child) {
   LOG(INFO) << "Adding window: " << child->id() << ": " << child->GetName();
   Setup();
 
   DCHECK(child);
   aura::Window* parent = window_tree_host_->window();
   if (!parent->Contains(child)) {
     parent->AddChild(child);
   }
 
-  parent->StackChildAtTop(child);
+  // Determine z-order relative to existing windows.
+  aura::Window::Windows windows = parent->children();
+  aura::Window* above = nullptr;
+  aura::Window* below = nullptr;
+  for (auto&& other : windows) {
+    if (other == child) {
+      continue;
+    }
+    if ((other->id() < child->id()) && (!below || other->id() > below->id())) {
+      below = other;
+    } else if ((other->id() > child->id()) &&
+               (!above || other->id() < above->id())) {
+      above = other;
+    }
+  }
+
+  // Adjust the z-order of the new child window.
+  if (above) {
+    parent->StackChildBelow(child, above);
+  } else if (below) {
+    parent->StackChildAbove(child, below);
+  } else {
+    parent->StackChildAtBottom(child);
+  }
   child->SetBounds(window_tree_host_->window()->bounds());
 }
 
 void CastWindowManagerAura::OnVSyncIntervalChanged(base::TimeDelta interval) {
   DCHECK(window_tree_host_.get());
   window_tree_host_->compositor()->SetAuthoritativeVSyncInterval(interval);
 }
 
 }  // namespace chromecast