2 files changed, 84 insertions, 0 deletions

diff --git a/base/id_map.h b/base/id_map.h
index bb9f05b..d3fc7b8 100644
--- a/base/id_map.h
+++ b/base/id_map.h
@@ -92,6 +92,17 @@ class IDMap : public base::NonThreadSafe {
     }
   }
 
+  void Clear() {
+    DCHECK(CalledOnValidThread());
+    if (iteration_depth_ == 0) {
+      Releaser<OS, 0>::release_all(&data_);
+    } else {
+      for (typename HashTable::iterator i = data_.begin();
+           i != data_.end(); ++i)
+        removed_ids_.insert(i->first);
+    }
+  }
+
   bool IsEmpty() const {
     DCHECK(CalledOnValidThread());
     return size() == 0u;
diff --git a/base/id_map_unittest.cc b/base/id_map_unittest.cc
index c4838ee..80c4c66 100644
--- a/base/id_map_unittest.cc
+++ b/base/id_map_unittest.cc
@@ -191,6 +191,42 @@ TEST_F(IDMapTest, AssignIterator) {
   EXPECT_EQ(0, map.iteration_depth());
 }
 
+TEST_F(IDMapTest, IteratorRemainsValidWhenClearing) {
+  IDMap<TestObject> map;
+
+  const int kCount = 5;
+  TestObject obj[kCount];
+  int32 ids[kCount];
+
+  for (int i = 0; i < kCount; i++)
+    ids[i] = map.Add(&obj[i]);
+
+  int counter = 0;
+  for (IDMap<TestObject>::const_iterator iter(&map);
+       !iter.IsAtEnd(); iter.Advance()) {
+    switch (counter) {
+      case 0:
+        EXPECT_EQ(ids[0], iter.GetCurrentKey());
+        EXPECT_EQ(&obj[0], iter.GetCurrentValue());
+        break;
+      case 1:
+        EXPECT_EQ(ids[1], iter.GetCurrentKey());
+        EXPECT_EQ(&obj[1], iter.GetCurrentValue());
+        map.Clear();
+        EXPECT_TRUE(map.IsEmpty());
+        EXPECT_EQ(0U, map.size());
+        break;
+      default:
+        FAIL() << "should not have that many elements";
+        break;
+    }
+    counter++;
+  }
+
+  EXPECT_TRUE(map.IsEmpty());
+  EXPECT_EQ(0U, map.size());
+}
+
 TEST_F(IDMapTest, OwningPointersDeletesThemOnRemove) {
   const int kCount = 3;
 
@@ -229,6 +265,43 @@ TEST_F(IDMapTest, OwningPointersDeletesThemOnRemove) {
   EXPECT_EQ(owned_del_count, kCount);
 }
 
+TEST_F(IDMapTest, OwningPointersDeletesThemOnClear) {
+  const int kCount = 3;
+
+  int external_del_count = 0;
+  DestructorCounter* external_obj[kCount];
+
+  int owned_del_count = 0;
+  DestructorCounter* owned_obj[kCount];
+
+  IDMap<DestructorCounter> map_external;
+  IDMap<DestructorCounter, IDMapOwnPointer> map_owned;
+
+  for (int i = 0; i < kCount; ++i) {
+    external_obj[i] = new DestructorCounter(&external_del_count);
+    map_external.Add(external_obj[i]);
+
+    owned_obj[i] = new DestructorCounter(&owned_del_count);
+    map_owned.Add(owned_obj[i]);
+  }
+
+  EXPECT_EQ(external_del_count, 0);
+  EXPECT_EQ(owned_del_count, 0);
+
+  map_external.Clear();
+  map_owned.Clear();
+
+  EXPECT_EQ(external_del_count, 0);
+  EXPECT_EQ(owned_del_count, kCount);
+
+  for (int i = 0; i < kCount; ++i) {
+    delete external_obj[i];
+  }
+
+  EXPECT_EQ(external_del_count, kCount);
+  EXPECT_EQ(owned_del_count, kCount);
+}
+
 TEST_F(IDMapTest, OwningPointersDeletesThemOnDestruct) {
   const int kCount = 3;