Rename ObserverList::has_observers to ObserverList::empty

Bug: 1155308
Change-Id: I6dc2ef187ccd5ab06b6b9b27b9d6ee2880ca8489
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2617203Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: danakj <danakj@chromium.org>
Commit-Queue: Mitsuru Oshima <oshima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#843121}

base/observer_list.h

@@ -319,7 +319,7 @@ class ObserverList {
     observers_count_ = 0;
   }
 
-  bool has_observers() const { return observers_count_ > 0; }
+  bool empty() const { return !observers_count_; }
 
   // Deprecated: use |has_observers()|.
   // TODO(1155308): migrate all callers and make this test only.

base/observer_list_unittest.cc

@@ -364,7 +364,7 @@ TYPED_TEST(ObserverListTest, CompactsWhenNoActiveIterator) {
   EXPECT_TRUE(col.HasObserver(&a));
   EXPECT_FALSE(col.HasObserver(&c));
 
-  EXPECT_TRUE(col.has_observers());
+  EXPECT_TRUE(!col.empty());
   EXPECT_TRUE(col.might_have_observers());
 
   using It = typename ObserverListConstFoo::const_iterator;
@@ -380,55 +380,55 @@ TYPED_TEST(ObserverListTest, CompactsWhenNoActiveIterator) {
     EXPECT_EQ(itb, it);
     EXPECT_EQ(++it, col.end());
 
-    EXPECT_TRUE(col.has_observers());
+    EXPECT_TRUE(!col.empty());
     EXPECT_TRUE(col.might_have_observers());
     EXPECT_EQ(&*ita, &a);
     EXPECT_EQ(&*itb, &b);
 
     ol.RemoveObserver(&a);
-    EXPECT_TRUE(col.has_observers());
+    EXPECT_TRUE(!col.empty());
     EXPECT_TRUE(col.might_have_observers());
     EXPECT_FALSE(col.HasObserver(&a));
     EXPECT_EQ(&*itb, &b);
 
     ol.RemoveObserver(&b);
-    EXPECT_FALSE(col.has_observers());
+    EXPECT_FALSE(!col.empty());
     EXPECT_TRUE(col.might_have_observers());
     EXPECT_FALSE(col.HasObserver(&a));
     EXPECT_FALSE(col.HasObserver(&b));
 
     it = It();
     ita = It();
-    EXPECT_FALSE(col.has_observers());
+    EXPECT_FALSE(!col.empty());
     EXPECT_TRUE(col.might_have_observers());
     ita = itb;
     itb = It();
-    EXPECT_FALSE(col.has_observers());
+    EXPECT_FALSE(!col.empty());
     EXPECT_TRUE(col.might_have_observers());
     ita = It();
-    EXPECT_FALSE(col.has_observers());
+    EXPECT_FALSE(!col.empty());
     EXPECT_FALSE(col.might_have_observers());
   }
 
   ol.AddObserver(&a);
   ol.AddObserver(&b);
-  EXPECT_TRUE(col.has_observers());
+  EXPECT_TRUE(!col.empty());
   EXPECT_TRUE(col.might_have_observers());
   ol.Clear();
-  EXPECT_FALSE(col.has_observers());
+  EXPECT_FALSE(!col.empty());
   EXPECT_FALSE(col.might_have_observers());
 
   ol.AddObserver(&a);
   ol.AddObserver(&b);
-  EXPECT_TRUE(col.has_observers());
+  EXPECT_TRUE(!col.empty());
   EXPECT_TRUE(col.might_have_observers());
   {
     const It it = col.begin();
     ol.Clear();
-    EXPECT_FALSE(col.has_observers());
+    EXPECT_FALSE(!col.empty());
     EXPECT_TRUE(col.might_have_observers());
   }
-  EXPECT_FALSE(col.has_observers());
+  EXPECT_FALSE(!col.empty());
   EXPECT_FALSE(col.might_have_observers());
 }
 
@@ -1013,7 +1013,7 @@ TEST_F(CheckedObserverListTest, CheckedObserver) {
     // On the non-death fork, no UAF occurs since the deleted observer is never
     // notified, but also the observer list still has |l2| in it. Check that.
     list->RemoveObserver(&l1);
-    EXPECT_TRUE(list->has_observers());
+    EXPECT_TRUE(!list->empty());
     EXPECT_TRUE(list->might_have_observers());
 
     // Now (in the non-death fork()) there's a problem. To delete |it|, we need

ui/compositor/compositor.cc

@@ -576,7 +576,7 @@ bool Compositor::HasObserver(const CompositorObserver* observer) const {
 }
 
 void Compositor::AddAnimationObserver(CompositorAnimationObserver* observer) {
-  if (!animation_observer_list_.has_observers()) {
+  if (animation_observer_list_.empty()) {
     for (auto& obs : observer_list_)
       obs.OnFirstAnimationStarted(this);
   }
@@ -589,7 +589,7 @@ void Compositor::RemoveAnimationObserver(
   if (!animation_observer_list_.HasObserver(observer))
     return;
   animation_observer_list_.RemoveObserver(observer);
-  if (!animation_observer_list_.has_observers()) {
+  if (animation_observer_list_.empty()) {
     for (auto& obs : observer_list_)
       obs.OnLastAnimationEnded(this);
   }

ui/compositor/total_animation_throughput_reporter.cc

@@ -71,7 +71,7 @@ TotalAnimationThroughputReporter::TotalAnimationThroughputReporter(
             report_once_callback_.is_null());
 
   compositor_->AddObserver(this);
-  if (compositor->animation_observer_list_.has_observers())
+  if (!compositor->animation_observer_list_.empty())
     OnFirstAnimationStarted(compositor_);
 }