Fix leak in ScopedVector<>::resize()

When resizing a vector to be smaller, delete the disappearing elements. This previously was a leak.  Interestingly, the one place this potential leak was tickled, history_backend.cc guarded itself against the leak, and we remove that now redundant guard here too.

R=willchan@chromium.org
BUG=None


Review URL: https://chromiumcodereview.appspot.com/11418140

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@169736 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 41 insertions, 1 deletions

diff --git a/base/memory/scoped_vector.h b/base/memory/scoped_vector.h
index feb0321..90a1f7d 100644
--- a/base/memory/scoped_vector.h
+++ b/base/memory/scoped_vector.h
@@ -74,7 +74,13 @@ class ScopedVector {
   }
 
   void reserve(size_t capacity) { v_.reserve(capacity); }
-  void resize(size_t new_size) { v_.resize(new_size); }
+
+  // Resize, deleting elements in the disappearing range if we are shrinking.
+  void resize(size_t new_size) {
+    if (v_.size() > new_size)
+      STLDeleteContainerPointers(v_.begin() + new_size, v_.end());
+    v_.resize(new_size);
+  }
 
   template<typename InputIterator>
   void assign(InputIterator begin, InputIterator end) {
diff --git a/base/memory/scoped_vector_unittest.cc b/base/memory/scoped_vector_unittest.cc
index 03774c5..17405e2 100644
--- a/base/memory/scoped_vector_unittest.cc
+++ b/base/memory/scoped_vector_unittest.cc
@@ -130,6 +130,40 @@ TEST(ScopedVectorTest, WeakClear) {
   EXPECT_EQ(static_cast<size_t>(0), scoped_vector.size());
 }
 
+TEST(ScopedVectorTest, ResizeShrink) {
+  LifeCycleWatcher first_watcher;
+  EXPECT_EQ(LC_INITIAL, first_watcher.life_cycle_state());
+  LifeCycleWatcher second_watcher;
+  EXPECT_EQ(LC_INITIAL, second_watcher.life_cycle_state());
+  ScopedVector<LifeCycleObject> scoped_vector;
+
+  scoped_vector.push_back(first_watcher.NewLifeCycleObject());
+  EXPECT_EQ(LC_CONSTRUCTED, first_watcher.life_cycle_state());
+  EXPECT_EQ(LC_INITIAL, second_watcher.life_cycle_state());
+
+  scoped_vector.push_back(second_watcher.NewLifeCycleObject());
+  EXPECT_EQ(LC_CONSTRUCTED, first_watcher.life_cycle_state());
+  EXPECT_EQ(LC_CONSTRUCTED, second_watcher.life_cycle_state());
+
+  // Test that shrinking a vector deletes elements in the dissapearing range.
+  scoped_vector.resize(1);
+  EXPECT_EQ(LC_CONSTRUCTED, first_watcher.life_cycle_state());
+  EXPECT_EQ(LC_DESTROYED, second_watcher.life_cycle_state());
+  EXPECT_EQ(1u, scoped_vector.size());
+}
+
+TEST(ScopedVectorTest, ResizeGrow) {
+  LifeCycleWatcher watcher;
+  EXPECT_EQ(LC_INITIAL, watcher.life_cycle_state());
+  ScopedVector<LifeCycleObject> scoped_vector;
+  scoped_vector.push_back(watcher.NewLifeCycleObject());
+  EXPECT_EQ(LC_CONSTRUCTED, watcher.life_cycle_state());
+
+  scoped_vector.resize(5);
+  EXPECT_EQ(LC_CONSTRUCTED, watcher.life_cycle_state());
+  EXPECT_EQ(5u, scoped_vector.size());
+}
+
 TEST(ScopedVectorTest, Scope) {
   LifeCycleWatcher watcher;
   EXPECT_EQ(LC_INITIAL, watcher.life_cycle_state());