Use locker when creating snapshot if necessary.

R=vogelheim@chromium.org

Review URL: https://codereview.chromium.org/962963007

Cr-Commit-Position: refs/heads/master@{#26964}

src/api.cc

@@ -590,10 +590,14 @@ void HandleScope::Initialize(Isolate* isolate) {
   // We do not want to check the correct usage of the Locker class all over the
   // place, so we do it only here: Without a HandleScope, an embedder can do
   // almost nothing, so it is enough to check in this central place.
-  Utils::ApiCheck(!v8::Locker::IsActive() ||
-                  internal_isolate->thread_manager()->IsLockedByCurrentThread(),
-                  "HandleScope::HandleScope",
-                  "Entering the V8 API without proper locking in place");
+  // We make an exception if the serializer is enabled, which means that the
+  // Isolate is exclusively used to create a snapshot.
+  Utils::ApiCheck(
+      !v8::Locker::IsActive() ||
+          internal_isolate->thread_manager()->IsLockedByCurrentThread() ||
+          internal_isolate->serializer_enabled(),
+      "HandleScope::HandleScope",
+      "Entering the V8 API without proper locking in place");
   i::HandleScopeData* current = internal_isolate->handle_scope_data();
   isolate_ = internal_isolate;
   prev_next_ = current->next;

test/cctest/test-serialize.cc

@@ -748,6 +748,42 @@ TEST(PerIsolateSnapshotBlobs) {
 }
 
 
+TEST(PerIsolateSnapshotBlobsWithLocker) {
+  // Disable experimental natives that are loaded after deserialization.
+  FLAG_harmony_shipping = false;
+  FlagList::EnforceFlagImplications();
+
+  v8::Isolate* isolate0 = v8::Isolate::New();
+  {
+    v8::Locker locker(isolate0);
+    v8::Isolate::Scope i_scope(isolate0);
+    v8::HandleScope h_scope(isolate0);
+    v8::Local<v8::Context> context = v8::Context::New(isolate0);
+    v8::Context::Scope c_scope(context);
+    CHECK_EQ(1, CompileRun("Math.cos(0)")->ToInt32(isolate0)->Int32Value());
+  }
+  isolate0->Dispose();
+
+  const char* source1 = "function f() { return 42; }";
+
+  v8::StartupData data1 = v8::V8::CreateSnapshotDataBlob(source1);
+
+  v8::Isolate::CreateParams params1;
+  params1.snapshot_blob = &data1;
+  v8::Isolate* isolate1 = v8::Isolate::New(params1);
+  {
+    v8::Locker locker(isolate1);
+    v8::Isolate::Scope i_scope(isolate1);
+    v8::HandleScope h_scope(isolate1);
+    v8::Local<v8::Context> context = v8::Context::New(isolate1);
+    delete[] data1.data;  // We can dispose of the snapshot blob now.
+    v8::Context::Scope c_scope(context);
+    CHECK_EQ(42, CompileRun("f()")->ToInt32(isolate1)->Int32Value());
+  }
+  isolate1->Dispose();
+}
+
+
 TEST(TestThatAlwaysSucceeds) {
 }