Migrate might_have_observer to empty in components/prefs and services/

Bug: 1155308
Change-Id: Ib42a0acc0a29beb35ced0e9cd717456c1d62a92e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2638540Reviewed-by: Gabriel Charette <gab@chromium.org>
Commit-Queue: Mitsuru Oshima <oshima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#845285}

components/prefs/default_pref_store.cc

@@ -30,7 +30,7 @@ void DefaultPrefStore::RemoveObserver(PrefStore::Observer* observer) {
 }
 
 bool DefaultPrefStore::HasObservers() const {
-  return observers_.might_have_observers();
+  return !observers_.empty();
 }
 
 void DefaultPrefStore::SetDefaultValue(const std::string& key, Value value) {

components/prefs/in_memory_pref_store.cc

@@ -36,7 +36,7 @@ void InMemoryPrefStore::RemoveObserver(PrefStore::Observer* observer) {
 }
 
 bool InMemoryPrefStore::HasObservers() const {
-  return observers_.might_have_observers();
+  return !observers_.empty();
 }
 
 bool InMemoryPrefStore::IsInitializationComplete() const {

components/prefs/json_pref_store.cc

@@ -196,8 +196,7 @@ void JsonPrefStore::RemoveObserver(PrefStore::Observer* observer) {
 
 bool JsonPrefStore::HasObservers() const {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
-
-  return observers_.might_have_observers();
+  return !observers_.empty();
 }
 
 bool JsonPrefStore::IsInitializationComplete() const {

components/prefs/overlay_user_pref_store.cc

@@ -63,7 +63,7 @@ void OverlayUserPrefStore::RemoveObserver(PrefStore::Observer* observer) {
 }
 
 bool OverlayUserPrefStore::HasObservers() const {
-  return observers_.might_have_observers();
+  return !observers_.empty();
 }
 
 bool OverlayUserPrefStore::IsInitializationComplete() const {

components/prefs/testing_pref_store.cc

@@ -44,7 +44,7 @@ void TestingPrefStore::RemoveObserver(PrefStore::Observer* observer) {
 }
 
 bool TestingPrefStore::HasObservers() const {
-  return observers_.might_have_observers();
+  return !observers_.empty();
 }
 
 bool TestingPrefStore::IsInitializationComplete() const {

components/prefs/value_map_pref_store.cc

@@ -30,7 +30,7 @@ void ValueMapPrefStore::RemoveObserver(PrefStore::Observer* observer) {
 }
 
 bool ValueMapPrefStore::HasObservers() const {
-  return observers_.might_have_observers();
+  return !observers_.empty();
 }
 
 void ValueMapPrefStore::SetValue(const std::string& key,

services/preferences/tracked/segregated_pref_store.cc

@@ -74,7 +74,7 @@ void SegregatedPrefStore::RemoveObserver(Observer* observer) {
 }
 
 bool SegregatedPrefStore::HasObservers() const {
-  return observers_.might_have_observers();
+  return !observers_.empty();
 }
 
 bool SegregatedPrefStore::IsInitializationComplete() const {