Refactor ozone drm cursor code for mojo

ui/ozone/platform/drm/host/drm_cursor.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 "ui/ozone/platform/drm/host/drm_cursor.h"
 
 #include "base/trace_event/trace_event.h"
 #include "ui/gfx/geometry/point_conversions.h"
 #include "ui/ozone/platform/drm/host/drm_window_host.h"
 #include "ui/ozone/platform/drm/host/drm_window_host_manager.h"
 
 #if defined(OS_CHROMEOS)
 #include "ui/events/ozone/chromeos/cursor_controller.h"
 #endif
 
 namespace ui {
 
 namespace {
 
 class NullProxy : public DrmCursorProxy {
  public:
   NullProxy() {}
   ~NullProxy() override {}
 
   void CursorSet(gfx::AcceleratedWidget window,
                  const std::vector<SkBitmap>& bitmaps,
                  const gfx::Point& point,
                  int frame_delay_ms) override {}
   void Move(gfx::AcceleratedWidget window, const gfx::Point& point) override {}
+  void InitializeOnEvdev() {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(NullProxy);
 };
 
 }  // namespace
 
 DrmCursor::DrmCursor(DrmWindowHostManager* window_manager)
     : window_(gfx::kNullAcceleratedWidget),
       window_manager_(window_manager),
@@ skipping 130 matching lines @@
 
   // TODO(spang): Moving between windows doesn't work here, but
   // is not needed for current uses.
   SetCursorLocationLocked(screen_location -
                           display_bounds_in_screen_.OffsetFromOrigin());
 
   SendCursorMoveLocked();
 }
 
 void DrmCursor::MoveCursor(const gfx::Vector2dF& delta) {
+  DCHECK(evdev_thread_checker_.CalledOnValidThread());
   TRACE_EVENT0("drmcursor", "DrmCursor::MoveCursor");
   base::AutoLock lock(lock_);
 
   if (window_ == gfx::kNullAcceleratedWidget)
     return;
 
   gfx::Point location;
 #if defined(OS_CHROMEOS)
   gfx::Vector2dF transformed_delta = delta;
   ui::CursorController::GetInstance()->ApplyCursorConfigForWindow(
@@ skipping 13 matching lines @@
 gfx::PointF DrmCursor::GetLocation() {
   base::AutoLock lock(lock_);
   return location_ + display_bounds_in_screen_.OffsetFromOrigin();
 }
 
 gfx::Rect DrmCursor::GetCursorConfinedBounds() {
   base::AutoLock lock(lock_);
   return confined_bounds_ + display_bounds_in_screen_.OffsetFromOrigin();
 }
 
+void DrmCursor::InitializeOnEvdev() {
+  evdev_thread_checker_.DetachFromThread();

[dnicoara, 2016/06/21 14:14:16]

Unless this is not called on the evdev thread you shouldn't detach. (In fact you
should DCHECK it since that makes sure |evdev_tread_checker_| is attached to the
correct thread)

[rjkroege, 2016/06/21 17:20:52]

The evdev_thread_checker_ is initialized on the main thread in the constructor.
So, I need to call DetachFromThread here to force the thread checker to be
attached to the evdev thread instead yes? This is true empirically: the thread
where this class is constructed is most definitely not the same thread as where
InitializeOnEvdev is called.

[dnicoara, 2016/06/21 17:38:18]

Ah, I see your reasoning. My understanding is that you should then call
DetachFromThread() when |evdev_thread_checker_| is created (in DrmCursor
constructor) and call CalledOnValidThread() in here. That way all call sites
that need to be done on the Evdev thread are checked.

+  proxy_->InitializeOnEvdev();
+}
+
 void DrmCursor::SetCursorLocationLocked(const gfx::PointF& location) {
   gfx::PointF clamped_location = location;
   clamped_location.SetToMax(gfx::PointF(confined_bounds_.origin()));
   // Right and bottom edges are exclusive.
   clamped_location.SetToMin(
       gfx::PointF(confined_bounds_.right() - 1, confined_bounds_.bottom() - 1));
 
   location_ = clamped_location;
 }
 
@@ skipping 26 matching lines @@
 }
 
 void DrmCursor::MoveLockTested(gfx::AcceleratedWidget window,
                                const gfx::Point& point) {
   lock_.AssertAcquired();
   proxy_->Move(window, point);
 }
 
 
 }  // namespace ui