ash: removes EnvObserver from WindowMirrorView

This code was necessary to avoid forcing a remote client to be visible
until occlusion tracking was enabled. Now that mash is no more, there are no
remote clients and this can be removed.

BUG=961763
TEST=none

Change-Id: I05d9603b82a14a1b394287540747e6b84269cb28
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1635292
Commit-Queue: Scott Violet <sky@chromium.org>
Reviewed-by: Ahmed Fakhry <afakhry@chromium.org>
Cr-Commit-Position: refs/heads/master@{#665553}

ash/wm/window_mirror_view.cc

@@ -102,17 +102,14 @@ void WindowMirrorView::AddedToWidget() {
   target_ = GetWidget()->GetNativeWindow();
   target_->TrackOcclusionState();
 
-  force_occlusion_tracker_visible_.reset();
-  env_observer_.RemoveAll();
-
-  // Wait for window-occlusion tracker to be running before forcing visibility.
-  // This is done to minimize the amount of work during the initial animation
-  // when entering overview. In particular, telling the remote client it is
-  // visible is likely to result in a fair amount of work.
-  if (aura::Env::GetInstance()->GetWindowOcclusionTracker()->IsPaused())
-    env_observer_.Add(aura::Env::GetInstance());
-  else
-    ForceVisibilityAndOcclusion();
+  if (source_) {
+    // Force the occlusion tracker to treat the source as visible.
+    force_occlusion_tracker_visible_ =
+        std::make_unique<aura::WindowOcclusionTracker::ScopedForceVisible>(
+            source_);
+  } else {
+    force_occlusion_tracker_visible_.reset();
+  }
 }
 
 void WindowMirrorView::RemovedFromWidget() {
@@ -163,26 +160,5 @@ gfx::Rect WindowMirrorView::GetClientAreaBounds() const {
   return client_view->ConvertRectToWidget(client_view->GetLocalBounds());
 }
 
-void WindowMirrorView::ForceVisibilityAndOcclusion() {
-  // Force the occlusion tracker to treat the source (or the desk container if
-  // source_ is on an inactive desk) as visible.
-  aura::Window* window_to_force_visible = source_;
-  aura::Window* desk_container =
-      desks_util::GetDeskContainerForContext(source_);
-  if (desk_container && !desks_util::IsActiveDeskContainer(desk_container))
-    window_to_force_visible = desk_container;
-
-  force_occlusion_tracker_visible_ =
-      std::make_unique<aura::WindowOcclusionTracker::ScopedForceVisible>(
-          window_to_force_visible);
-}
-
-void WindowMirrorView::OnWindowOcclusionTrackingResumed() {
-  // Skip if the source_ has already been removed.
-  if (source_)
-    ForceVisibilityAndOcclusion();
-  env_observer_.RemoveAll();
-}
-
 }  // namespace wm
 }  // namespace ash

ash/wm/window_mirror_view.h

@@ -9,9 +9,6 @@
 
 #include "ash/ash_export.h"
 #include "base/macros.h"
-#include "base/scoped_observer.h"
-#include "ui/aura/env.h"
-#include "ui/aura/env_observer.h"
 #include "ui/aura/window_observer.h"
 #include "ui/aura/window_occlusion_tracker.h"
 #include "ui/views/view.h"
@@ -29,8 +26,7 @@ namespace wm {
 
 // A view that mirrors the client area of a single (source) window.
 class ASH_EXPORT WindowMirrorView : public views::View,
-                                    public aura::WindowObserver,
-                                    public aura::EnvObserver {
+                                    public aura::WindowObserver {
  public:
   WindowMirrorView(aura::Window* source, bool trilinear_filtering_on_init);
   ~WindowMirrorView() override;
@@ -63,11 +59,6 @@ class ASH_EXPORT WindowMirrorView : public views::View,
   // coordinate space.
   gfx::Rect GetClientAreaBounds() const;
 
-  void ForceVisibilityAndOcclusion();
-
-  // aura::EnvObserver:
-  void OnWindowOcclusionTrackingResumed() override;
-
   // The original window that is being represented by |this|.
   aura::Window* source_;
 
@@ -85,8 +76,6 @@ class ASH_EXPORT WindowMirrorView : public views::View,
   std::unique_ptr<aura::WindowOcclusionTracker::ScopedForceVisible>
       force_occlusion_tracker_visible_;
 
-  ScopedObserver<aura::Env, aura::EnvObserver> env_observer_{this};
-
   DISALLOW_COPY_AND_ASSIGN(WindowMirrorView);
 };