Update the CodeEventObserver of a ProfilerListener when a v8::CpuProfiler is restarted

Fixes a segfault that occurs when v8::CpuProfilers are restarted caused
by the reuse of a stale CodeEventObserver.

Bug: chromium:929928
Change-Id: I5d5f7eaf5cd903910130cdb0cfec8c3fd6608edd
Reviewed-on: https://chromium-review.googlesource.com/c/1459740Reviewed-by: Alexei Filippov <alph@chromium.org>
Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Commit-Queue: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59506}

src/profiler/cpu-profiler.cc

@@ -382,7 +382,9 @@ void CpuProfiler::StartProcessorIfNotStarted() {
   }
   processor_.reset(new SamplingEventsProcessor(isolate_, generator_.get(),
                                                sampling_interval_));
-  if (!profiler_listener_) {
+  if (profiler_listener_) {
+    profiler_listener_->set_observer(processor_.get());
+  } else {
     profiler_listener_.reset(new ProfilerListener(isolate_, processor_.get()));
   }
   logger->AddCodeEventListener(profiler_listener_.get());

src/profiler/profiler-listener.h

@@ -75,6 +75,8 @@ class ProfilerListener : public CodeEventListener {
     return function_and_resource_names_.GetConsName(prefix, name);
   }
 
+  void set_observer(CodeEventObserver* observer) { observer_ = observer; }
+
  private:
   void AttachDeoptInlinedFrames(Code code, CodeDeoptEventRecord* rec);
   Name InferScriptName(Name name, SharedFunctionInfo info);

test/cctest/test-cpu-profiler.cc

@@ -2688,6 +2688,22 @@ TEST(MultipleProfilers) {
   profiler2->StopProfiling("2");
 }
 
+// Tests that logged CodeCreateEvent calls do not crash a reused CpuProfiler.
+// crbug.com/929928
+TEST(CrashReusedProfiler) {
+  LocalContext env;
+  i::Isolate* isolate = CcTest::i_isolate();
+  i::HandleScope scope(isolate);
+
+  std::unique_ptr<CpuProfiler> profiler(new CpuProfiler(isolate));
+  profiler->StartProfiling("1");
+  profiler->StopProfiling("1");
+
+  profiler->StartProfiling("2");
+  CreateCode(&env);
+  profiler->StopProfiling("2");
+}
+
 void ProfileSomeCode(v8::Isolate* isolate) {
   v8::Isolate::Scope isolate_scope(isolate);
   v8::HandleScope scope(isolate);