[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 caea27e7a569cad1b99efef6093c0da570deb4a8..5db5a9b7d03e79b9f50217ef8ffe02e86beebe15 100644
--- a/gin/isolate_holder.cc
+++ b/gin/isolate_holder.cc
@@ -34,23 +34,50 @@ 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,
+                    kDefault) {}
 
 IsolateHolder::IsolateHolder(
     scoped_refptr<base::SingleThreadTaskRunner> task_runner,
     AccessMode access_mode,
-    AllowAtomicsWaitMode atomics_wait_mode)
-    : access_mode_(access_mode) {
+    AllowAtomicsWaitMode atomics_wait_mode,
+    intptr_t* reference,
+    V8ContextMode context_mode)
+    : access_mode_(access_mode), v8_context_mode_(context_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();
-  params.constraints.ConfigureDefaults(base::SysInfo::AmountOfPhysicalMemory(),
-                                       base::SysInfo::AmountOfVirtualMemory());
-  params.array_buffer_allocator = allocator;
-  params.allow_atomics_wait = atomics_wait_mode == kAllowAtomicsWait;
-  isolate_ = v8::Isolate::New(params);
+
+  if (v8_context_mode_ == kTakeSnapshot) {
+    DCHECK(reference);
+    snapshot_creator_.reset(new v8::SnapshotCreator(reference));
+    isolate_ = snapshot_creator_->GetIsolate();
+    isolate_->Exit();
+  } else {
+    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();
+    params.constraints.ConfigureDefaults(
+        base::SysInfo::AmountOfPhysicalMemory(),
+        base::SysInfo::AmountOfVirtualMemory());
+    params.array_buffer_allocator = allocator;
+    params.allow_atomics_wait = atomics_wait_mode == kAllowAtomicsWait;
+    v8_context_mode_ = kDefault;
+    if (reference) {
+      V8Initializer::GetV8ContextData(&startup_data_.data,
+                                      &startup_data_.raw_size);
+      if (startup_data_.data) {
+        params.snapshot_blob = &startup_data_;
+        params.external_references = reference;
+        v8_context_mode_ = kUseSnapshot;
+      }
+    }
+    isolate_ = v8::Isolate::New(params);
+  }
+
   isolate_data_.reset(
       new PerIsolateData(isolate_, allocator, access_mode, task_runner));
   isolate_memory_dump_provider_.reset(new V8IsolateMemoryDumpProvider(this));
@@ -84,7 +111,7 @@ IsolateHolder::~IsolateHolder() {
   isolate_memory_dump_provider_.reset();
   isolate_data_.reset();
   isolate_->Dispose();
-  isolate_ = NULL;
+  isolate_ = nullptr;
 }
 
 // static