Fix LifeCycleWatcher in ScopedVectorTest to not be referenced after being destructed.

base/memory/scoped_vector_unittest.cc

Index: base/memory/scoped_vector_unittest.cc
diff --git a/base/memory/scoped_vector_unittest.cc b/base/memory/scoped_vector_unittest.cc
index 220cfb04687c74fbf13f950bd52b757cf340ca44..4dee9c9004e93e3c0a0ddfdaa58ec6d9079439fa 100644
--- a/base/memory/scoped_vector_unittest.cc
+++ b/base/memory/scoped_vector_unittest.cc
@@ -24,7 +24,8 @@ class LifeCycleObject {
   };
 
   ~LifeCycleObject() {
-    observer_->OnLifeCycleDestroy(this);
+    if (observer_)
+      observer_->OnLifeCycleDestroy(this);
   }
 
  private:
@@ -35,6 +36,10 @@ class LifeCycleObject {
     observer_->OnLifeCycleConstruct(this);
   }
 
+  void DisconnectObserver() {
+    observer_ = nullptr;
+  }
+
   Observer* observer_;
 
   DISALLOW_COPY_AND_ASSIGN(LifeCycleObject);
@@ -62,7 +67,13 @@ enum LifeCycleState {
 class LifeCycleWatcher : public LifeCycleObject::Observer {
  public:
   LifeCycleWatcher() : life_cycle_state_(LC_INITIAL) {}
-  ~LifeCycleWatcher() override {}
+  ~LifeCycleWatcher() override {
+    // Stop watching the watched object. Without this, the object's destructor

[danakj, 2015/09/24 17:43:51]

Alternatively, you could just keep the watcher alive in the test this is causing
a problem for? Which test(s) are wrong here?

[Anand Mistry (off Chromium), 2015/09/24 21:56:27]

The two tests that fail are WeakClear and InsertRange. Both create watched
object thats aren't deleted by ScopedVector, so it's up to LifeCycleWatcher to
clean up at the end of the test.

+    // will call into OnLifeCycleDestroy when destructed, which happens after
+    // this destructor has finished running.
+    if (constructed_life_cycle_object_)
+      constructed_life_cycle_object_->DisconnectObserver();
+  }
 
   // Assert INITIAL -> CONSTRUCTED and no LifeCycleObject associated with this
   // LifeCycleWatcher.