Retire ScopedObserver in /chrome/browser/ui/views/bubble.

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=romanarora@chromium.org

Bug: 1145565
Change-Id: Ic27dc466d5f152cb73a2f767720032eb6bf02597
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2548021
Auto-Submit: Sigurður Ásgeirsson <siggi@chromium.org>
Commit-Queue: Thomas Lukaszewicz <tluk@chromium.org>
Reviewed-by: Thomas Lukaszewicz <tluk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#829240}

chrome/browser/ui/views/bubble/webui_bubble_manager.cc

@@ -54,7 +54,7 @@ bool WebUIBubbleManagerBase::ShowBubble() {
   bubble_view_ = WebUIBubbleDialogView::CreateWebUIBubbleDialog(
       std::make_unique<WebUIBubbleDialogView>(anchor_view_,
                                               std::move(cached_web_view_)));
-  observed_bubble_widget_.Add(bubble_view_->GetWidget());
+  bubble_widget_observation_.Observe(bubble_view_->GetWidget());
   close_bubble_helper_ = std::make_unique<CloseBubbleOnTabActivationHelper>(
       bubble_view_.get(), BrowserList::GetInstance()->GetLastActive());
   return true;
@@ -76,7 +76,7 @@ void WebUIBubbleManagerBase::OnWidgetDestroying(views::Widget* widget) {
   DCHECK(bubble_view_);
   DCHECK_EQ(bubble_view_->GetWidget(), widget);
   cached_web_view_ = bubble_view_->RemoveWebView();
-  observed_bubble_widget_.Remove(bubble_view_->GetWidget());
+  bubble_widget_observation_.RemoveObservation();
   DCHECK(close_bubble_helper_);
   close_bubble_helper_.reset();
   cache_timer_->Reset();

chrome/browser/ui/views/bubble/webui_bubble_manager.h

@@ -8,7 +8,7 @@
 #include <memory>
 #include <utility>
 
-#include "base/scoped_observer.h"
+#include "base/scoped_observation.h"
 #include "chrome/browser/extensions/chrome_extension_web_contents_observer.h"
 #include "chrome/browser/ui/views/bubble/webui_bubble_view.h"
 #include "chrome/browser/ui/views/close_bubble_on_tab_activation_helper.h"
@@ -77,8 +77,8 @@ class WebUIBubbleManagerBase : public views::WidgetObserver {
   // A timer controlling how long the |cached_web_view_| is cached for.
   std::unique_ptr<base::RetainingOneShotTimer> cache_timer_;
 
-  ScopedObserver<views::Widget, views::WidgetObserver> observed_bubble_widget_{
-      this};
+  base::ScopedObservation<views::Widget, views::WidgetObserver>
+      bubble_widget_observation_{this};
 
   // This is necessary to prevent a bug closing the active tab in the bubble.
   // See https://crbug.com/1139028.