perf: don't use JSON to send the result of ipcRenderer.sendSync. (#8953)

* Don't use JSON to send the result of `ipcRenderer.sendSync`.

- Change the return type of AtomViewHostMsg_Message_Sync from `base::string16`
  to `base::ListValue`
- Adjust lib/browser/api/web-contents.js and /lib/renderer/api/ipc-renderer.js
  to wrap/unwrap return values to/from array, instead of
  serializing/deserializing JSON.

This change can greatly improve `ipcRenderer.sendSync` calls where the return
value contains Buffer instances, because those are converted to Array before
being serialized to JSON(which has no efficient way of representing byte
arrays).

A simple benchmark where remote.require('fs') was used to read a 16mb file got
at least 5x faster, not to mention it used a lot less memory.  This difference
tends increases with larger buffers.

* Don't base64 encode Buffers

* Don't allocate V8ValueConverter on the heap

* Replace hidden global.sandbox with NodeBindings::IsInitialized()

* Refactoring: check NodeBindings::IsInitialized() in V8ValueConverter

* Refactor problematic test to make it more reliable

* Add tests for NaN and Infinity

atom/common/api/api_messages.h

@@ -31,7 +31,7 @@ IPC_MESSAGE_ROUTED2(AtomFrameHostMsg_Message,
 IPC_SYNC_MESSAGE_ROUTED2_1(AtomFrameHostMsg_Message_Sync,
                            base::string16 /* channel */,
                            base::ListValue /* arguments */,
-                           base::string16 /* result (in JSON) */)
+                           base::ListValue /* result */)
 
 IPC_MESSAGE_ROUTED3(AtomFrameMsg_Message,
                     bool /* send_to_all */,

atom/common/native_mate_converters/v8_value_converter.cc

@@ -13,6 +13,7 @@
 #include "base/values.h"
 #include "native_mate/dictionary.h"
 
+#include "atom/common/node_bindings.h"
 #include "atom/common/node_includes.h"
 
 namespace atom {
@@ -136,10 +137,6 @@ void V8ValueConverter::SetStripNullFromObjects(bool val) {
   strip_null_from_objects_ = val;
 }
 
-void V8ValueConverter::SetDisableNode(bool val) {
-  disable_node_ = val;
-}
-
 v8::Local<v8::Value> V8ValueConverter::ToV8Value(
     const base::Value* value,
     v8::Local<v8::Context> context) const {
@@ -253,7 +250,7 @@ v8::Local<v8::Value> V8ValueConverter::ToArrayBuffer(
   const char* data = value->GetBlob().data();
   size_t length = value->GetBlob().size();
 
-  if (!disable_node_) {
+  if (NodeBindings::IsInitialized()) {
     return node::Buffer::Copy(isolate, data, length).ToLocalChecked();
   }
 

atom/common/native_mate_converters/v8_value_converter.h

@@ -24,7 +24,6 @@ class V8ValueConverter {
   void SetRegExpAllowed(bool val);
   void SetFunctionAllowed(bool val);
   void SetStripNullFromObjects(bool val);
-  void SetDisableNode(bool val);
   v8::Local<v8::Value> ToV8Value(const base::Value* value,
                                  v8::Local<v8::Context> context) const;
   base::Value* FromV8Value(v8::Local<v8::Value> value,
@@ -63,13 +62,6 @@ class V8ValueConverter {
   // If true, we will convert Function JavaScript objects to dictionaries.
   bool function_allowed_ = false;
 
-  // If true, will not use node::Buffer::Copy to deserialize byte arrays.
-  // node::Buffer::Copy depends on a working node.js environment, and this is
-  // not desirable in sandboxed renderers. That means Buffer instances sent from
-  // browser process will be deserialized as browserify-based Buffer(which are
-  // wrappers around Uint8Array).
-  bool disable_node_ = false;
-
   // If true, undefined and null values are ignored when converting v8 objects
   // into Values.
   bool strip_null_from_objects_ = false;

atom/common/node_bindings.cc

@@ -104,6 +104,8 @@ void stop_and_close_uv_loop(uv_loop_t* loop) {
   uv_loop_close(loop);
 }
 
+bool g_is_initialized = false;
+
 }  // namespace
 
 namespace atom {
@@ -178,6 +180,10 @@ void NodeBindings::RegisterBuiltinModules() {
 #undef V
 }
 
+bool NodeBindings::IsInitialized() {
+  return g_is_initialized;
+}
+
 void NodeBindings::Initialize() {
   // Open node's error reporting system for browser process.
   node::g_standalone_mode = browser_env_ == BROWSER;
@@ -203,6 +209,8 @@ void NodeBindings::Initialize() {
   if (browser_env_ == BROWSER || env->HasVar("ELECTRON_DEFAULT_ERROR_MODE"))
     SetErrorMode(GetErrorMode() & ~SEM_NOGPFAULTERRORBOX);
 #endif
+
+  g_is_initialized = true;
 }
 
 node::Environment* NodeBindings::CreateEnvironment(

atom/common/node_bindings.h

@@ -32,6 +32,7 @@ class NodeBindings {
 
   static NodeBindings* Create(BrowserEnvironment browser_env);
   static void RegisterBuiltinModules();
+  static bool IsInitialized();
 
   virtual ~NodeBindings();