[Bindings] Create and use V8 context snapshots

gin/isolate_holder.cc

Index: gin/isolate_holder.cc
diff --git a/gin/isolate_holder.cc b/gin/isolate_holder.cc
index 2e707359ca70f51778e179a74c26c95060ed52a1..1d9b0d8c49c423ddfa4aefef1474410fc6de2ce2 100644
--- a/gin/isolate_holder.cc
+++ b/gin/isolate_holder.cc
@@ -35,15 +35,22 @@ IsolateHolder::IsolateHolder(
 IsolateHolder::IsolateHolder(
     scoped_refptr<base::SingleThreadTaskRunner> task_runner,
     AccessMode access_mode)
-    : IsolateHolder(std::move(task_runner), access_mode, kAllowAtomicsWait) {}
+    : IsolateHolder(std::move(task_runner),
+                    access_mode,
+                    kAllowAtomicsWait,
+                    nullptr,
+                    nullptr) {}
 
 IsolateHolder::IsolateHolder(
     scoped_refptr<base::SingleThreadTaskRunner> task_runner,
     AccessMode access_mode,
-    AllowAtomicsWaitMode atomics_wait_mode)
+    AllowAtomicsWaitMode atomics_wait_mode,
+    intptr_t* reference,
+    v8::StartupData* startup_data)
     : access_mode_(access_mode) {
   v8::ArrayBuffer::Allocator* allocator = g_array_buffer_allocator;
   CHECK(allocator) << "You need to invoke gin::IsolateHolder::Initialize first";
+
   v8::Isolate::CreateParams params;
   params.entry_hook = DebugImpl::GetFunctionEntryHook();
   params.code_event_handler = DebugImpl::GetJitCodeEventHandler();
@@ -51,7 +58,18 @@ IsolateHolder::IsolateHolder(
                                        base::SysInfo::AmountOfVirtualMemory());
   params.array_buffer_allocator = allocator;
   params.allow_atomics_wait = atomics_wait_mode == kAllowAtomicsWait;
+  params.external_references = reference;
+
+  if (startup_data) {
+    CHECK(reference);
+    V8Initializer::GetV8ContextData(&startup_data->data,
+                                    &startup_data->raw_size);
+    if (startup_data->data) {
+      params.snapshot_blob = startup_data;
+    }

[Yuki, 2017/05/30 14:35:56]

What happens if GetV8ContextData fails to load the snapshot blob?
Should we report an error if (!startup_data->data)?

[peria, 2017/06/01 08:33:32]

I can't agree to make it an error. Even if Chrome fails to load blob,
it can work with kDontUseSnapshot mode.

+  }
   isolate_ = v8::Isolate::New(params);
+
   isolate_data_.reset(
       new PerIsolateData(isolate_, allocator, access_mode, task_runner));
   isolate_memory_dump_provider_.reset(new V8IsolateMemoryDumpProvider(this));
@@ -68,6 +86,26 @@ IsolateHolder::IsolateHolder(
 #endif
 }
 
+IsolateHolder::IsolateHolder(v8::Isolate* isolate)
+    : isolate_(isolate), access_mode_(kSingleThread) {

[Yuki, 2017/05/30 14:35:56]

Could you avoid copy&pasting?  Can we have a helper function instead?

The former constructor above should call the helper function with the created
isolate.

[peria, 2017/06/01 08:33:32]

Done.
Will move to another CL.

+  v8::ArrayBuffer::Allocator* allocator = g_array_buffer_allocator;
+  CHECK(allocator) << "You need to invoke gin::IsolateHolder::Initialize first";
+  isolate_data_.reset(
+      new PerIsolateData(isolate_, allocator, access_mode_, nullptr));
+  isolate_memory_dump_provider_.reset(new V8IsolateMemoryDumpProvider(this));
+#if defined(OS_WIN)
+  {
+    void* code_range;
+    size_t size;
+    isolate_->GetCodeRange(&code_range, &size);
+    Debug::CodeRangeCreatedCallback callback =
+        DebugImpl::GetCodeRangeCreatedCallback();
+    if (code_range && size && callback)
+      callback(code_range, size);
+  }
+#endif
+}
+
 IsolateHolder::~IsolateHolder() {
   if (task_observer_.get())
     base::MessageLoop::current()->RemoveTaskObserver(task_observer_.get());
@@ -85,7 +123,7 @@ IsolateHolder::~IsolateHolder() {
   isolate_memory_dump_provider_.reset();
   isolate_data_.reset();
   isolate_->Dispose();
-  isolate_ = NULL;
+  isolate_ = nullptr;
 }
 
 // static