Correctly track the target window's lifetime in WindowResizer

The recorder is created in constructor, so only scenario that I can
think of is that resizer is destroyed during SetBounds.

I also added CHECK to catch the scenario where the resizer is destroyed
during resize for other reasons. I'll remove the code once fix is confirmed.

Bug: 970911
Test: None. Repro step is unknown and this is speculative fix.
Change-Id: I58e20fe916664867b776d36b7720a2a2fb5ee357
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1655968Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Mitsuru Oshima <oshima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#668458}

ash/wm/window_resizer.cc

@@ -85,7 +85,10 @@ WindowResizer::WindowResizer(wm::WindowState* window_state)
   DCHECK(window_state_->drag_details());
 }
 
-WindowResizer::~WindowResizer() = default;
+WindowResizer::~WindowResizer() {
+  if (destroyed_)
+    *destroyed_ = true;
+}
 
 // static
 int WindowResizer::GetBoundsChangeForWindowComponent(int component) {
@@ -269,14 +272,20 @@ bool WindowResizer::IsBottomEdge(int window_component) {
 void WindowResizer::SetBoundsDuringResize(const gfx::Rect& bounds) {
   aura::Window* window = GetTarget();
   DCHECK(window);
-  const gfx::Rect original_bounds = window->bounds();
-  window->SetBounds(bounds);
+  bool destroyed = false;
+  destroyed_ = &destroyed;
   aura::WindowTracker tracker;
   tracker.Add(window);
+
+  const gfx::Rect original_bounds = window->bounds();
+  window->SetBounds(bounds);
+
   if (tracker.windows().empty())
     return;  // Assume we've been destroyed.
   if (bounds.size() == original_bounds.size())
     return;
+  CHECK(!destroyed);
+  destroyed_ = nullptr;
   recorder_->RequestNext();
 }
 

ash/wm/window_resizer.h

@@ -110,6 +110,8 @@ class ASH_EXPORT WindowResizer {
   // Updates |new_bounds| to adhere to the aspect ratio.
   void CalculateBoundsWithAspectRatio(float aspect_ratio,
                                       gfx::Rect* new_bounds);
+  // Remove once it is confirmed that crbug.com/970911 is fixed.
+  bool* destroyed_ = nullptr;
 
   std::unique_ptr<PresentationTimeRecorder> recorder_;