exo: Fix dragging edge cases

components/exo/shell_surface.cc

Index: components/exo/shell_surface.cc
diff --git a/components/exo/shell_surface.cc b/components/exo/shell_surface.cc
index e51f8c00195d1ff9df7cccf6b35e53e4431cca36..5a7a634c343985d215e213893878c79822024dfc 100644
--- a/components/exo/shell_surface.cc
+++ b/components/exo/shell_surface.cc
@@ -373,6 +373,7 @@ ShellSurface::ShellSurface(Surface* surface,
       can_minimize_(can_minimize),
       container_(container) {
   WMHelper::GetInstance()->AddActivationObserver(this);
+  WMHelper::GetInstance()->AddShellObserver(this);
   surface_->SetSurfaceDelegate(this);
   surface_->AddSurfaceObserver(this);
   surface_->window()->Show();
@@ -405,6 +406,7 @@ ShellSurface::~ShellSurface() {
     widget_->CloseNow();
   }
   WMHelper::GetInstance()->RemoveActivationObserver(this);
+  WMHelper::GetInstance()->RemoveShellObserver(this);
   if (parent_)
     parent_->RemoveObserver(this);
   if (surface_) {
@@ -934,6 +936,8 @@ void ShellSurface::OnPreWindowStateTypeChange(
   ash::wm::WindowStateType new_type = window_state->GetStateType();
   if (ash::wm::IsMaximizedOrFullscreenOrPinnedWindowStateType(old_type) ||
       ash::wm::IsMaximizedOrFullscreenOrPinnedWindowStateType(new_type)) {
+    EndDragOrMove(false /* revert */);

[reveman, 2017/01/23 20:23:48]

how is other chrome windows handling this?

[Dominik Laskowski, 2017/01/23 23:01:36]

It's not handled. If you enter full screen after dragging (but not dropping) a
Chrome window to another display, its content disappears and the full screen key
stops working.

[reveman, 2017/01/26 06:50:21]

That sounds like a bug. Is there a more general way to fix this than just making
exo/ handle it correctly?

+
     // When transitioning in/out of maximized or fullscreen mode we need to
     // make sure we have a configure callback before we allow the default
     // cross-fade animations. The configure callback provides a mechanism for
@@ -1028,6 +1032,18 @@ void ShellSurface::OnWindowActivated(
 }
 
 ////////////////////////////////////////////////////////////////////////////////
+// WMHelper::ShellObserver overrides:
+
+void ShellSurface::OnOverviewModeStarted() {
+  EndDragOrMove(false /* revert */);

[reveman, 2017/01/23 20:23:48]

is this also a problem for non-exo window dragging? or are they already doing
this?

[Dominik Laskowski, 2017/01/23 23:01:36]

Yes, entering/exiting overview mode while dragging is broken for Chrome windows
too. You can keep dragging in overview mode, leading to inconsistent state. I
have another small patch that does the same for Ash.

[reveman, 2017/01/26 06:50:21]

Ok, let's do Ash first and once that lands we'll make a consistent change here.

+  ignore_widget_bounds_changes_ = true;

[reveman, 2017/01/23 20:23:48]

why is this needed? seems fragile to rely on us detecting when we enter this
specific mode..

[Dominik Laskowski, 2017/01/23 23:01:36]

When entering overview mode, a lost focus event causes Android to abort the
drag, but it's possible for geometry updates to be in flight at that time. This
flag is needed to discard those updates.

[reveman, 2017/01/26 06:50:21]

Why do they need to be discarded? Doesn't this leave us in a state where chrome
is not in sync with the android state? 

+}
+
+void ShellSurface::OnOverviewModeEnded() {
+  ignore_widget_bounds_changes_ = false;
+}
+
+////////////////////////////////////////////////////////////////////////////////
 // WMHelper::AccessibilityObserver overrides:
 
 void ShellSurface::OnAccessibilityModeChanged() {
@@ -1410,8 +1426,8 @@ void ShellSurface::UpdateWidgetBounds() {
     return;
   }
 
-  // 2) When a window is being dragged.
-  if (IsResizing())
+  // 2) When a window is being dragged, or is being moved by the shell.
+  if (IsResizing() || ignore_widget_bounds_changes_)
     return;
 
   // Return early if there is pending configure requests.