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

chromecast/graphics/cast_window_manager_aura.cc

Index: chromecast/graphics/cast_window_manager_aura.cc
diff --git a/chromecast/graphics/cast_window_manager_aura.cc b/chromecast/graphics/cast_window_manager_aura.cc
index b4d9dbcd0896f1180c237be5c1cfcbb851fe8dae..8c04b5a1a4a1b0c728038c543496a302044a55ff 100644
--- a/chromecast/graphics/cast_window_manager_aura.cc
+++ b/chromecast/graphics/cast_window_manager_aura.cc
@@ -6,6 +6,7 @@
 
 #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"
@@ -136,6 +137,7 @@ void CastWindowManagerAura::Setup() {
   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()));
 
@@ -150,8 +152,10 @@ 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();
 }
 
@@ -165,7 +169,30 @@ void CastWindowManagerAura::AddWindow(gfx::NativeView 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());
 }