[code health] components/web_cache: Remove NotificationService usage.

Use RenderProcessHostObserver and RenderProcessHostCreationObserver
APIs to replace the usage of NotificationService.

BUG=357627

Change-Id: Idae690c3cc8bb7fffdca0558301b938df3ea1441
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1844274Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Sadrul Chowdhury <sadrul@chromium.org>
Cr-Commit-Position: refs/heads/master@{#703726}

components/web_cache/browser/web_cache_manager.cc

@@ -11,7 +11,6 @@
 #include "base/bind.h"
 #include "base/compiler_specific.h"
 #include "base/location.h"
-#include "base/memory/singleton.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/single_thread_task_runner.h"
 #include "base/system/sys_info.h"
@@ -19,8 +18,6 @@
 #include "base/time/time.h"
 #include "components/prefs/pref_registry_simple.h"
 #include "components/prefs/pref_service.h"
-#include "content/public/browser/notification_service.h"
-#include "content/public/browser/notification_types.h"
 #include "content/public/browser/render_process_host.h"
 #include "services/service_manager/public/cpp/interface_provider.h"
 
@@ -57,17 +54,12 @@ int GetDefaultCacheSize() {
 
 // static
 WebCacheManager* WebCacheManager::GetInstance() {
-  return base::Singleton<WebCacheManager>::get();
+  static base::NoDestructor<WebCacheManager> s_instance;
+  return s_instance.get();
 }
 
 WebCacheManager::WebCacheManager()
     : global_size_limit_(GetDefaultGlobalSizeLimit()) {
-  registrar_.Add(this, content::NOTIFICATION_RENDERER_PROCESS_CREATED,
-                 content::NotificationService::AllBrowserContextsAndSources());
-  registrar_.Add(this, content::NOTIFICATION_RENDERER_PROCESS_CLOSED,
-                 content::NotificationService::AllBrowserContextsAndSources());
-  registrar_.Add(this, content::NOTIFICATION_RENDERER_PROCESS_TERMINATED,
-                 content::NotificationService::AllBrowserContextsAndSources());
 }
 
 WebCacheManager::~WebCacheManager() {
@@ -164,27 +156,22 @@ void WebCacheManager::ClearCacheOnNavigation() {
   ClearRendererCache(inactive_renderers_, ON_NAVIGATION);
 }
 
-void WebCacheManager::Observe(int type,
-                              const content::NotificationSource& source,
-                              const content::NotificationDetails& details) {
-  switch (type) {
-    case content::NOTIFICATION_RENDERER_PROCESS_CREATED: {
-      content::RenderProcessHost* process =
-          content::Source<content::RenderProcessHost>(source).ptr();
-      Add(process->GetID());
-      break;
-    }
-    case content::NOTIFICATION_RENDERER_PROCESS_CLOSED:
-    case content::NOTIFICATION_RENDERER_PROCESS_TERMINATED: {
-      content::RenderProcessHost* process =
-          content::Source<content::RenderProcessHost>(source).ptr();
-      Remove(process->GetID());
-      break;
-    }
-    default:
-      NOTREACHED();
-      break;
-  }
+void WebCacheManager::OnRenderProcessHostCreated(
+    content::RenderProcessHost* process_host) {
+  Add(process_host->GetID());
+  rph_observers_.Add(process_host);
+}
+
+void WebCacheManager::RenderProcessExited(
+    content::RenderProcessHost* process_host,
+    const content::ChildProcessTerminationInfo& info) {
+  RenderProcessHostDestroyed(process_host);
+}
+
+void WebCacheManager::RenderProcessHostDestroyed(
+    content::RenderProcessHost* process_host) {
+  rph_observers_.Remove(process_host);
+  Remove(process_host->GetID());
 }
 
 // static

components/web_cache/browser/web_cache_manager.h

@@ -18,22 +18,20 @@
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
+#include "base/no_destructor.h"
+#include "base/scoped_observer.h"
 #include "base/time/time.h"
 #include "components/web_cache/public/mojom/web_cache.mojom.h"
-#include "content/public/browser/notification_observer.h"
-#include "content/public/browser/notification_registrar.h"
+#include "content/public/browser/render_process_host_creation_observer.h"
+#include "content/public/browser/render_process_host_observer.h"
 #include "mojo/public/cpp/bindings/remote.h"
 
-namespace base {
-template<typename Type>
-struct DefaultSingletonTraits;
-}  // namespace base
-
 namespace web_cache {
 
 // Note: memory usage uses uint64_t because potentially the browser could be
 // 32 bit and the renderers 64 bits.
-class WebCacheManager : public content::NotificationObserver {
+class WebCacheManager : public content::RenderProcessHostCreationObserver,
+                        public content::RenderProcessHostObserver {
   friend class WebCacheManagerTest;
   FRIEND_TEST_ALL_PREFIXES(
       WebCacheManagerTest,
@@ -102,10 +100,15 @@ class WebCacheManager : public content::NotificationObserver {
   // to a different website.
   void ClearCacheOnNavigation();
 
-  // content::NotificationObserver implementation:
-  void Observe(int type,
-               const content::NotificationSource& source,
-               const content::NotificationDetails& details) override;
+  // content::RenderProcessHostCreationObserver:
+  void OnRenderProcessHostCreated(
+      content::RenderProcessHost* process_host) override;
+
+  // content::RenderProcessHostObserver:
+  void RenderProcessExited(
+      content::RenderProcessHost* host,
+      const content::ChildProcessTerminationInfo& info) override;
+  void RenderProcessHostDestroyed(content::RenderProcessHost* host) override;
 
   // Gets the default global size limit.  This interrogates system metrics to
   // tune the default size to the current system.
@@ -136,9 +139,10 @@ class WebCacheManager : public content::NotificationObserver {
   // The key is the unique id of every render process host.
   typedef std::map<int, mojo::Remote<mojom::WebCache>> WebCacheServicesMap;
 
-  // This class is a singleton.  Do not instantiate directly.
+  // This class is a singleton.  Do not instantiate directly. Call GetInstance()
+  // instead.
   WebCacheManager();
-  friend struct base::DefaultSingletonTraits<WebCacheManager>;
+  friend class base::NoDestructor<WebCacheManager>;
 
   ~WebCacheManager() override;
 
@@ -238,12 +242,13 @@ class WebCacheManager : public content::NotificationObserver {
   // recently than they have been active.
   std::set<int> inactive_renderers_;
 
-  content::NotificationRegistrar registrar_;
-
   // Maps every renderer_id with its corresponding
   // mojo::Remote<mojom::WebCache>.
   WebCacheServicesMap web_cache_services_;
 
+  ScopedObserver<content::RenderProcessHost, content::RenderProcessHostObserver>
+      rph_observers_{this};
+
   base::WeakPtrFactory<WebCacheManager> weak_factory_{this};
 
   DISALLOW_COPY_AND_ASSIGN(WebCacheManager);

components/web_cache/browser/web_cache_manager_unittest.cc

@@ -93,8 +93,10 @@ class WebCacheManagerTest : public testing::Test {
   WebCacheManager* manager() { return &manager_; }
 
  private:
-  WebCacheManager manager_;
+  // Create the environment before creating the WebCacheManager, because the
+  // latter depends on the UI thread to have been set up correctly.
   content::BrowserTaskEnvironment task_environment_;
+  WebCacheManager manager_;
 };
 
 // static