[a11y] Update caret blink interval immediately

Adds a native theme observer to the pref watcher that
will be notified when the caret blink interval changes.

Bug: b/259374492
Change-Id: I4f3097c115399bd848b250e1690cbc2a4b351495
AX-Relnotes: N/A
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5467975
Commit-Queue: Katie Dektar <katie@chromium.org>
Reviewed-by: Dominic Battre <battre@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1290671}

ash/accessibility/accessibility_controller.cc

@@ -2713,12 +2713,12 @@ void AccessibilityController::UpdateCaretBlinkIntervalFromPrefs() const {
       active_user_prefs_->GetInteger(prefs::kAccessibilityCaretBlinkInterval));
   auto* native_theme_dark = ui::NativeTheme::GetInstanceForDarkUI();
   native_theme_dark->set_caret_blink_interval(caret_blink_interval);
-  native_theme_dark->NotifyOnNativeThemeUpdated();
   auto* native_theme_web = ui::NativeTheme::GetInstanceForWeb();
   native_theme_web->set_caret_blink_interval(caret_blink_interval);
-  native_theme_web->NotifyOnNativeThemeUpdated();
   auto* native_theme = ui::NativeTheme::GetInstanceForNativeUi();
   native_theme->set_caret_blink_interval(caret_blink_interval);
+  native_theme_dark->NotifyOnNativeThemeUpdated();
+  native_theme_web->NotifyOnNativeThemeUpdated();
   native_theme->NotifyOnNativeThemeUpdated();
 }
 

chrome/browser/ui/prefs/pref_watcher.cc

@@ -17,6 +17,7 @@
 #include "components/live_caption/pref_names.h"
 #include "components/privacy_sandbox/tracking_protection_settings.h"
 #include "third_party/blink/public/common/renderer_preferences/renderer_preferences.h"
+#include "ui/native_theme/native_theme.h"
 
 #if BUILDFLAG(IS_CHROMEOS_ASH)
 #include "ash/constants/ash_pref_names.h"
@@ -84,6 +85,7 @@ PrefWatcher::PrefWatcher(Profile* profile)
   CHECK(tracking_protection_settings_);
   tracking_protection_settings_observation_.Observe(
       tracking_protection_settings_);
+  native_theme_observation_.Observe(ui::NativeTheme::GetInstanceForWeb());
 
   profile_pref_change_registrar_.Init(profile_->GetPrefs());
 
@@ -149,6 +151,11 @@ void PrefWatcher::Shutdown() {
   local_state_pref_change_registrar_.RemoveAll();
 }
 
+void PrefWatcher::OnNativeThemeUpdated(
+    ui::NativeTheme* observed_theme) {
+  UpdateRendererPreferences();
+}
+
 void PrefWatcher::OnDoNotTrackEnabledChanged() {
   UpdateRendererPreferences();
 }

chrome/browser/ui/prefs/pref_watcher.h

@@ -7,6 +7,7 @@
 
 #include "base/memory/raw_ptr.h"
 #include "base/memory/singleton.h"
+#include "base/scoped_observation.h"
 #include "chrome/browser/profiles/profile_keyed_service_factory.h"
 #include "components/keyed_service/core/keyed_service.h"
 #include "components/prefs/pref_change_registrar.h"
@@ -14,6 +15,7 @@
 #include "components/privacy_sandbox/tracking_protection_settings_observer.h"
 #include "mojo/public/cpp/bindings/remote_set.h"
 #include "third_party/blink/public/mojom/renderer_preference_watcher.mojom.h"
+#include "ui/native_theme/native_theme_observer.h"
 
 class Profile;
 class PrefsTabHelper;
@@ -21,7 +23,8 @@ class PrefsTabHelper;
 // Watches updates in WebKitPreferences and blink::RendererPreferences, and
 // notifies tab helpers and registered watchers of those updates.
 class PrefWatcher : public KeyedService,
-                    public privacy_sandbox::TrackingProtectionSettingsObserver {
+                    public privacy_sandbox::TrackingProtectionSettingsObserver,
+                    public ui::NativeThemeObserver {
  public:
   explicit PrefWatcher(Profile* profile);
   ~PrefWatcher() override;
@@ -37,6 +40,9 @@ class PrefWatcher : public KeyedService,
   // KeyedService overrides:
   void Shutdown() override;
 
+  // ui::NativeThemeObserver:
+  void OnNativeThemeUpdated(ui::NativeTheme* observed_theme) override;
+
   void OnDoNotTrackEnabledChanged() override;
 
   void UpdateRendererPreferences();
@@ -62,6 +68,9 @@ class PrefWatcher : public KeyedService,
   // preference changes, use |tab_helpers_|.
   mojo::RemoteSet<blink::mojom::RendererPreferenceWatcher>
       renderer_preference_watchers_;
+
+    base::ScopedObservation<ui::NativeTheme, ui::NativeThemeObserver>
+      native_theme_observation_{this};
 };
 
 class PrefWatcherFactory : public ProfileKeyedServiceFactory {