Tab dragging as implemented as a mus API.

components/mus/public/cpp/lib/window_tree_client.cc

 // Copyright 2014 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 "components/mus/public/cpp/window_tree_client.h"
 
 #include <stddef.h>
 
 #include <string>
 #include <utility>
@@ skipping 214 matching lines @@
 }
 
 bool WindowTreeClient::OwnsWindow(Window* window) const {
   // Windows created via CreateTopLevelWindow() are not owned by us, but have
   // our client id.
   return HiWord(server_id(window)) == client_id_ &&
          roots_.count(window) == 0;
 }
 
 void WindowTreeClient::SetBounds(Window* window,
-                                     const gfx::Rect& old_bounds,
-                                     const gfx::Rect& bounds) {
+                                 const gfx::Rect& old_bounds,
+                                 const gfx::Rect& bounds) {
   DCHECK(tree_);
   const uint32_t change_id = ScheduleInFlightChange(
       base::WrapUnique(new InFlightBoundsChange(window, old_bounds)));
   tree_->SetWindowBounds(change_id, server_id(window), bounds);
 }
 
 void WindowTreeClient::SetCapture(Window* window) {
   // In order for us to get here we had to have exposed a window, which implies
   // we got a client.
   DCHECK(tree_);
@@ skipping 326 matching lines @@
 
   window_manager_delegate_->OnWmNewDisplay(root, display);
 }
 
 void WindowTreeClient::OnReceivedCursorLocationMemory(
     mojo::ScopedSharedBufferHandle handle) {
   cursor_location_mapping_ = handle->Map(sizeof(base::subtle::Atomic32));
   DCHECK(cursor_location_mapping_);
 }
 
+void WindowTreeClient::OnWmMoveLoopCompleted(uint32_t change_id,
+                                             bool completed) {
+  if (window_manager_internal_client_) {
+    window_manager_internal_client_->OnWmMoveLoopCompleted(change_id,
+                                                           completed);
+  }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // WindowTreeClient, WindowTreeClient implementation:
 
 void WindowTreeClient::SetDeleteOnNoRoots(bool value) {
   delete_on_no_roots_ = value;
 }
 
 const std::set<Window*>& WindowTreeClient::GetRoots() {
   return roots_;
 }
@@ skipping 24 matching lines @@
   if (matcher.is_null()) {
     has_event_observer_ = false;
     tree_->SetEventObserver(nullptr, 0u);
   } else {
     has_event_observer_ = true;
     event_observer_id_++;
     tree_->SetEventObserver(std::move(matcher), event_observer_id_);
   }
 }
 
+void WindowTreeClient::PerformWindowMove(
+    Window* window,
+    ::mus::mojom::MoveLoopSource source,
+    const gfx::Point& cursor_location,
+    const base::Callback<void(bool)>& callback) {
+  DCHECK(on_current_move_finished_.is_null());
+  on_current_move_finished_ = callback;
+
+  current_move_loop_change_ = ScheduleInFlightChange(
+      base::WrapUnique(new InFlightMoveLoopChange(window)));
+  // Tell the window manager to take over moving us.
+  tree_->PerformWindowMove(current_move_loop_change_, window->server_id(),
+                           source, cursor_location);
+}
+
+void WindowTreeClient::CancelWindowMove(Window* window) {
+  tree_->CancelWindowMove(window->server_id());
+}
+
 Window* WindowTreeClient::NewWindow(
     const Window::SharedProperties* properties) {
   return NewWindowImpl(NewWindowType::CHILD, properties);
 }
 
 Window* WindowTreeClient::NewTopLevelWindow(
     const Window::SharedProperties* properties) {
   Window* window = NewWindowImpl(NewWindowType::TOP_LEVEL, properties);
   // Assume newly created top level windows are drawn by default, otherwise
   // requests to focus will fail. We will get the real value in
@@ skipping 375 matching lines @@
   if (!success)
     change->ChangeFailed();
 
   InFlightChange* next_change = GetOldestInFlightChangeMatching(*change);
   if (next_change) {
     if (!success)
       next_change->SetRevertValueFrom(*change);
   } else if (!success) {
     change->Revert();
   }
+
+  if (change_id == current_move_loop_change_) {
+    on_current_move_finished_.Run(success);
+    on_current_move_finished_.Reset();
+    current_move_loop_change_ = 0;

[sky, 2016/06/29 00:04:08]

Please move current_move_loop_change_ = 0 before the Run(), that way we don't
think we're in a move if the caller calls back.

+  }
 }
 
 void WindowTreeClient::GetWindowManager(
     mojo::AssociatedInterfaceRequest<WindowManager> internal) {
   window_manager_internal_.reset(
       new mojo::AssociatedBinding<mojom::WindowManager>(this,
                                                         std::move(internal)));
 }
 
 void WindowTreeClient::RequestClose(uint32_t window_id) {
@@ skipping 30 matching lines @@
       // the client applies the bounds we set below.
       result = bounds == transit_bounds;
       window->SetBounds(bounds);
     }
   }
   if (window_manager_internal_client_)
     window_manager_internal_client_->WmResponse(change_id, result);
 }
 
 void WindowTreeClient::WmSetProperty(uint32_t change_id,
-                                         Id window_id,
-                                         const mojo::String& name,
-                                         mojo::Array<uint8_t> transit_data) {
+                                     Id window_id,
+                                     const mojo::String& name,
+                                     mojo::Array<uint8_t> transit_data) {
   Window* window = GetWindowByServerId(window_id);
   bool result = false;
   if (window) {
     DCHECK(window_manager_delegate_);
     std::unique_ptr<std::vector<uint8_t>> data;
     if (!transit_data.is_null()) {
       data.reset(
           new std::vector<uint8_t>(transit_data.To<std::vector<uint8_t>>()));
     }
     result = window_manager_delegate_->OnWmSetProperty(window, name, &data);
@@ skipping 16 matching lines @@
   Window* window =
       window_manager_delegate_->OnWmCreateTopLevelWindow(&properties);
   embedded_windows_[requesting_client_id].insert(window);
   if (window_manager_internal_client_) {
     window_manager_internal_client_->OnWmCreatedTopLevelWindow(
         change_id, server_id(window));
   }
 }
 
 void WindowTreeClient::WmClientJankinessChanged(ClientSpecificId client_id,
-                                                    bool janky) {
+                                                bool janky) {
   if (window_manager_delegate_) {
     auto it = embedded_windows_.find(client_id);
     CHECK(it != embedded_windows_.end());
     window_manager_delegate_->OnWmClientJankinessChanged(
         embedded_windows_[client_id], janky);
   }
 }
 
+void WindowTreeClient::WmPerformMoveLoop(uint32_t change_id,
+                                         Id window_id,
+                                         ::mus::mojom::MoveLoopSource source,
+                                         const gfx::Point& cursor_location) {
+  if (window_manager_delegate_) {

[sky, 2016/06/29 00:04:08]

If there is no window for id, immediately call OnWmMoveLoopCompleted.

+    window_manager_delegate_->OnWmPerformMoveLoop(
+        GetWindowByServerId(window_id), source, cursor_location,
+        base::Bind(&WindowTreeClient::OnWmMoveLoopCompleted,
+                   weak_factory_.GetWeakPtr(), change_id));
+  }
+}
+
+void WindowTreeClient::WmCancelMoveLoop(uint32_t window_id) {
+  if (window_manager_delegate_)

[sky, 2016/06/29 00:04:08]

As WmCancelMoveLoop is async, it's entirely possible that
OnWmMoveLoopCompleted() has already been called. This code should protect
against that, otherwise the delegate is going to be in a very confused state.

+    window_manager_delegate_->OnWmCancelMoveLoop(
+        GetWindowByServerId(window_id));
+}
+
 void WindowTreeClient::OnAccelerator(uint32_t id,
                                      std::unique_ptr<ui::Event> event) {
   DCHECK(event);
   window_manager_delegate_->OnAccelerator(id, *event.get());
 }
 
 void WindowTreeClient::SetFrameDecorationValues(
     mojom::FrameDecorationValuesPtr values) {
   if (window_manager_internal_client_) {
     window_manager_internal_client_->WmSetFrameDecorationValues(
         std::move(values));
   }
 }
 
 void WindowTreeClient::SetNonClientCursor(Window* window,
-                                              mus::mojom::Cursor cursor_id) {
+                                          mus::mojom::Cursor cursor_id) {
   window_manager_internal_client_->WmSetNonClientCursor(server_id(window),
                                                         cursor_id);
 }
 
 void WindowTreeClient::AddAccelerator(
     uint32_t id,
     mojom::EventMatcherPtr event_matcher,
     const base::Callback<void(bool)>& callback) {
   if (window_manager_internal_client_) {
     window_manager_internal_client_->AddAccelerator(
@@ skipping 26 matching lines @@
     Window* window,
     const gfx::Vector2d& offset,
     const gfx::Insets& hit_area) {
   if (window_manager_internal_client_) {
     window_manager_internal_client_->SetUnderlaySurfaceOffsetAndExtendedHitArea(
         server_id(window), offset.x(), offset.y(), hit_area);
   }
 }
 
 }  // namespace mus