exo: Fix cursor scale when crossing displays

components/exo/pointer.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 "components/exo/pointer.h"
 
 #include "ash/public/cpp/shell_window_ids.h"
 #include "cc/output/copy_output_request.h"
 #include "cc/output/copy_output_result.h"
 #include "components/exo/pointer_delegate.h"
@@ skipping 247 matching lines @@
   // Reparent the cursor to the root window where the mouse is located.
   if (container->GetRootWindow() != cursor_->GetRootWindow()) {
     if (cursor_->parent())
       cursor_->parent()->RemoveChild(cursor_.get());
     container->AddChild(cursor_.get());
   }
 
   auto info = helper->GetDisplayInfo(display.id());
   display_scale_ = info.GetEffectiveUIScale() * info.device_scale_factor();
   device_scale_factor_ = display.device_scale_factor();
+
+  if (focus_ && surface_) {
+    // Capture is asynchronous, so avoid rendering old cursor in the meantime.

[reveman, 2017/04/28 21:37:09]

I'm still not convinced that we should do this. One cursor transition instead of
two seems better imo. I would hate to see the cursor flicker. Much better to
show an incorrectly sized cursor for a few ms imo. How about just a simple
CaptureCursor() call here for now so we can land this fix and you can then file
a bug for the incorrect size problem and use that bug to convince me that
showing no cursor for a few ms is better. Is that OK?

[oshima, 2017/05/01 22:18:04]

Yes, we need a better way to handle custom cursors in general.
(high contract, large cursors are others)

Let me file a bug(s).

I agree that it's probably better to not to reset to none, but i'll leave it to
you guys.

[Dominik Laskowski, 2017/05/06 00:34:45]

Done, and filed a bug: http://crbug.com/719116

+    cursor_capture_weak_ptr_factory_.InvalidateWeakPtrs();
+    UpdateCursor(ui::CursorType::kNone);
+    CaptureCursor();
+  }
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // SurfaceDelegate overrides:
 
 void Pointer::OnSurfaceCommit() {
   surface_->CheckIfSurfaceHierarchyNeedsCommitToNewSurfaces();
   surface_->CommitSurfaceHierarchy();
 
   // Capture new cursor to reflect result of commit.
@@ skipping 90 matching lines @@
   if (!root_window)
     return;
 
   aura::client::CursorClient* cursor_client =
       aura::client::GetCursorClient(root_window);
   if (cursor_client)
     cursor_client->SetCursor(cursor);
 }
 
 }  // namespace exo