Retire ScopedObserver in /components/arc/intent_helper.

ScopedObserver is being deprecated in favor of two new classes:
- base::ScopedObservation for observers that only ever observe
  a single source.
- base::ScopedMultiSourceObservation for observers that do or may
  observe more than a single source.

This CL was uploaded by git cl split.

R=djacobo@chromium.org

Bug: 1145565
Change-Id: I436bf817ddb0820060ddcc817c324cf2ae5c9cee
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2532715Reviewed-by: Dominick Ng <dominickn@chromium.org>
Reviewed-by: David Jacobo <djacobo@chromium.org>
Commit-Queue: David Jacobo <djacobo@chromium.org>
Auto-Submit: Sigurður Ásgeirsson <siggi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#827867}

components/arc/intent_helper/custom_tab.cc

@@ -20,7 +20,7 @@ namespace arc {
 
 CustomTab::CustomTab(aura::Window* arc_app_window)
     : arc_app_window_(arc_app_window) {
-  arc_app_window_observer_.Add(arc_app_window_);
+  arc_app_window_observation_.Observe(arc_app_window_);
   host_->set_owned_by_client();
   auto* const widget = views::Widget::GetWidgetForNativeWindow(arc_app_window_);
   DCHECK(widget);
@@ -35,7 +35,7 @@ void CustomTab::Attach(gfx::NativeView view) {
   host_->Attach(view);
   aura::Window* const container = host_->GetNativeViewContainer();
   container->SetEventTargeter(std::make_unique<aura::WindowTargeter>());
-  other_windows_observer_.Add(container);
+  other_windows_observation_.Observe(container);
   EnsureWindowOrders();
   UpdateHostBounds(arc_app_window_);
 }
@@ -48,7 +48,7 @@ void CustomTab::OnWindowBoundsChanged(aura::Window* window,
                                       const gfx::Rect& old_bounds,
                                       const gfx::Rect& new_bounds,
                                       ui::PropertyChangeReason reason) {
-  if (arc_app_window_observer_.IsObserving(window) &&
+  if (arc_app_window_observation_.IsObservingSource(window) &&
       old_bounds.size() != new_bounds.size()) {
     UpdateHostBounds(window);
   }
@@ -69,10 +69,10 @@ void CustomTab::OnWindowStackingChanged(aura::Window* window) {
 }
 
 void CustomTab::OnWindowDestroying(aura::Window* window) {
-  if (arc_app_window_observer_.IsObserving(window))
-    arc_app_window_observer_.Remove(window);
-  if (other_windows_observer_.IsObserving(window))
-    other_windows_observer_.Remove(window);
+  if (arc_app_window_observation_.IsObservingSource(window))
+    arc_app_window_observation_.RemoveObservation();
+  if (other_windows_observation_.IsObservingSource(window))
+    other_windows_observation_.RemoveObservation();
 }
 
 void CustomTab::UpdateHostBounds(aura::Window* arc_app_window) {

components/arc/intent_helper/custom_tab.h

@@ -8,7 +8,7 @@
 #include <memory>
 
 #include "base/macros.h"
-#include "base/scoped_observer.h"
+#include "base/scoped_observation.h"
 #include "components/arc/arc_export.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_observer.h"
@@ -53,10 +53,10 @@ class ARC_EXPORT CustomTab : public aura::WindowObserver {
   std::unique_ptr<views::NativeViewHost> host_ =
       std::make_unique<views::NativeViewHost>();
   aura::Window* const arc_app_window_;
-  ScopedObserver<aura::Window, aura::WindowObserver> arc_app_window_observer_{
-      this};
-  ScopedObserver<aura::Window, aura::WindowObserver> other_windows_observer_{
-      this};
+  base::ScopedObservation<aura::Window, aura::WindowObserver>
+      arc_app_window_observation_{this};
+  base::ScopedObservation<aura::Window, aura::WindowObserver>
+      other_windows_observation_{this};
   base::WeakPtrFactory<CustomTab> weak_ptr_factory_{this};
 };