[fuzzer] Use std::unique_ptr for the FuzzerSupport

The FuzzerSupport was keeping a single instance of itself. With this CL,
this instance is now stored in a unique_ptr. Therefore it is not
necessary to register an onExit callback to delete the FuzzerSupport
instance.

Drive-by changes: Some cleanup with the FuzzerSupport.

R=clemensh@chromium.org

Bug: chromium:787723
Change-Id: I5188c7aa7e778ccd45fc80ed0115c947d23a0dee
Reviewed-on: https://chromium-review.googlesource.com/792949Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49723}

test/fuzzer/fuzzer-support.cc

@@ -14,19 +14,6 @@
 
 namespace v8_fuzzer {
 
-namespace {
-
-FuzzerSupport* g_fuzzer_support = nullptr;
-
-void DeleteFuzzerSupport() {
-  if (g_fuzzer_support) {
-    delete g_fuzzer_support;
-    g_fuzzer_support = nullptr;
-  }
-}
-
-}  // namespace
-
 FuzzerSupport::FuzzerSupport(int* argc, char*** argv) {
   v8::internal::FLAG_expose_gc = true;
   v8::V8::SetFlagsFromCommandLine(argc, *argv, true);
@@ -72,10 +59,20 @@ FuzzerSupport::~FuzzerSupport() {
   v8::V8::ShutdownPlatform();
 }
 
+std::unique_ptr<FuzzerSupport> FuzzerSupport::fuzzer_support_;
+
 // static
-FuzzerSupport* FuzzerSupport::Get() { return g_fuzzer_support; }
+void FuzzerSupport::InitializeFuzzerSupport(int* argc, char*** argv) {
+  DCHECK_NULL(FuzzerSupport::fuzzer_support_);
+  FuzzerSupport::fuzzer_support_ =
+      v8::base::make_unique<v8_fuzzer::FuzzerSupport>(argc, argv);
+}
 
-v8::Isolate* FuzzerSupport::GetIsolate() const { return isolate_; }
+// static
+FuzzerSupport* FuzzerSupport::Get() {
+  DCHECK_NOT_NULL(FuzzerSupport::fuzzer_support_);
+  return FuzzerSupport::fuzzer_support_.get();
+}
 
 v8::Local<v8::Context> FuzzerSupport::GetContext() {
   v8::Isolate::Scope isolate_scope(isolate_);
@@ -93,7 +90,6 @@ bool FuzzerSupport::PumpMessageLoop(
 }  // namespace v8_fuzzer
 
 extern "C" int LLVMFuzzerInitialize(int* argc, char*** argv) {
-  v8_fuzzer::g_fuzzer_support = new v8_fuzzer::FuzzerSupport(argc, argv);
-  atexit(&v8_fuzzer::DeleteFuzzerSupport);
+  v8_fuzzer::FuzzerSupport::InitializeFuzzerSupport(argc, argv);
   return 0;
 }

test/fuzzer/fuzzer-support.h

@@ -13,12 +13,17 @@ namespace v8_fuzzer {
 class FuzzerSupport {
  public:
   FuzzerSupport(int* argc, char*** argv);
+
   ~FuzzerSupport();
 
+  static void InitializeFuzzerSupport(int* argc, char*** argv);
+
   static FuzzerSupport* Get();
 
-  v8::Isolate* GetIsolate() const;
+  v8::Isolate* GetIsolate() const { return isolate_; }
+
   v8::Local<v8::Context> GetContext();
+
   bool PumpMessageLoop(v8::platform::MessageLoopBehavior =
                            v8::platform::MessageLoopBehavior::kDoNotWait);
 
@@ -27,6 +32,7 @@ class FuzzerSupport {
   FuzzerSupport(const FuzzerSupport&);
   FuzzerSupport& operator=(const FuzzerSupport&);
 
+  static std::unique_ptr<FuzzerSupport> fuzzer_support_;
   std::unique_ptr<v8::Platform> platform_;
   v8::ArrayBuffer::Allocator* allocator_;
   v8::Isolate* isolate_;