c++ / mojo changes for 'external window mode'

services/ui/ws/display.cc

 // Copyright 2015 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 "services/ui/ws/display.h"
 
 #include <set>
 #include <utility>
 #include <vector>
 
@@ skipping 186 matching lines @@
 }
 
 void Display::SetSize(const gfx::Size& size) {
   platform_display_->SetViewportSize(size);
 }
 
 void Display::SetTitle(const std::string& title) {
   platform_display_->SetTitle(base::UTF8ToUTF16(title));
 }
 
 void Display::InitWindowManagerDisplayRoots() {

[kylechar, 2017/02/28 21:17:16]

In general you probably don't want to ever hit any of the methods with
"WindowManager" in the name in external window mode. Of course the code path
doesn't work like that now but it would make more sense if you split some of
this logic up.

If I understand correctly, binding_ == nullptr means internal mode and you could
sprinkle DCHECK(!binding_) in a few methods to ensure we only do WM related
stuff in internal mode.

   if (binding_) {
     std::unique_ptr<WindowManagerDisplayRoot> display_root_ptr(
         new WindowManagerDisplayRoot(this));
     WindowManagerDisplayRoot* display_root = display_root_ptr.get();
     // For this case we never create additional displays roots, so any
     // id works.
     window_manager_display_root_map_[service_manager::mojom::kRootUserID] =
         display_root_ptr.get();
-    WindowTree* window_tree = binding_->CreateWindowTree(display_root->root());
+
+    DCHECK(window_server_->window_tree_host_factory());
+    WindowTree* window_tree =
+        window_server_->window_tree_host_factory()->window_tree();
+    window_tree->AddRoot(display_root->root());
+    window_tree->DoOnEmbed(nullptr /*mojom::WindowTreePtr*/,

[fwang, 2017/02/28 08:23:53]

Is commenting nullptr parameter something common in chromium style?

+                           display_root->root());
+
+    window_tree->ConfigureWindowManager();
     display_root->window_manager_state_ = window_tree->window_manager_state();
     window_tree->window_manager_state()->AddWindowManagerDisplayRoot(
         std::move(display_root_ptr));
   } else {
     CreateWindowManagerDisplayRootsFromFactories();
   }
   display_manager()->OnDisplayUpdate(this);
 }
 
 void Display::CreateWindowManagerDisplayRootsFromFactories() {
@@ skipping 166 matching lines @@
 }
 
 void Display::OnWindowManagerWindowTreeFactoryReady(
     WindowManagerWindowTreeFactory* factory) {
   if (!binding_)
     CreateWindowManagerDisplayRootFromFactory(factory);
 }
 
 }  // namespace ws
 }  // namespace ui