Retire ScopedObserver in /components/permissions.

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=andypaicu@chromium.org

Bug: 1145565
Change-Id: I9075e3c8594c64f0a4a4d2b5e5320e1d21308e32
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2533135
Commit-Queue: Sigurður Ásgeirsson <siggi@chromium.org>
Commit-Queue: Andy Paicu <andypaicu@chromium.org>
Reviewed-by: Andy Paicu <andypaicu@chromium.org>
Auto-Submit: Sigurður Ásgeirsson <siggi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#826772}

components/permissions/test/permission_request_observer.cc

@@ -8,7 +8,7 @@ namespace permissions {
 
 PermissionRequestObserver::PermissionRequestObserver(
     content::WebContents* web_contents) {
-  observer_.Add(PermissionRequestManager::FromWebContents(web_contents));
+  observation_.Observe(PermissionRequestManager::FromWebContents(web_contents));
 }
 
 PermissionRequestObserver::~PermissionRequestObserver() = default;

components/permissions/test/permission_request_observer.h

@@ -6,7 +6,7 @@
 #define COMPONENTS_PERMISSIONS_TEST_PERMISSION_REQUEST_OBSERVER_H_
 
 #include "base/run_loop.h"
-#include "base/scoped_observer.h"
+#include "base/scoped_observation.h"
 #include "components/permissions/permission_request_manager.h"
 
 namespace permissions {
@@ -30,8 +30,9 @@ class PermissionRequestObserver : public PermissionRequestManager::Observer {
   void OnBubbleAdded() override;
 
  private:
-  ScopedObserver<PermissionRequestManager, PermissionRequestManager::Observer>
-      observer_{this};
+  base::ScopedObservation<PermissionRequestManager,
+                          PermissionRequestManager::Observer>
+      observation_{this};
   base::RunLoop loop_;
   bool request_shown_ = false;
 };