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

spec/api-browser-window-spec.js

@@ -1381,24 +1381,25 @@ describe('BrowserWindow module', () => {
         })
         let htmlPath = path.join(fixtures, 'api', 'sandbox.html?verify-ipc-sender')
         const pageUrl = 'file://' + htmlPath
-        w.loadURL(pageUrl)
+        let childWc
         w.webContents.once('new-window', (e, url, frameName, disposition, options) => {
-          let parentWc = w.webContents
-          let childWc = options.webContents
-          assert.notEqual(parentWc, childWc)
-          ipcMain.once('parent-ready', function (event) {
-            assert.equal(parentWc, event.sender)
-            parentWc.send('verified')
-          })
-          ipcMain.once('child-ready', function (event) {
-            assert.equal(childWc, event.sender)
-            childWc.send('verified')
-          })
-          waitForEvents(ipcMain, [
-            'parent-answer',
-            'child-answer'
-          ], done)
+          childWc = options.webContents
+          assert.notEqual(w.webContents, childWc)
         })
+        ipcMain.once('parent-ready', function (event) {
+          assert.equal(w.webContents, event.sender)
+          event.sender.send('verified')
+        })
+        ipcMain.once('child-ready', function (event) {
+          assert(childWc)
+          assert.equal(childWc, event.sender)
+          event.sender.send('verified')
+        })
+        waitForEvents(ipcMain, [
+          'parent-answer',
+          'child-answer'
+        ], done)
+        w.loadURL(pageUrl)
       })
 
       describe('event handling', () => {

spec/api-remote-spec.js

@@ -237,6 +237,16 @@ describe('remote module', () => {
     const print = path.join(fixtures, 'module', 'print_name.js')
     const printName = remote.require(print)
 
+    it('converts NaN to undefined', () => {
+      assert.strictEqual(printName.getNaN(), undefined)
+      assert.strictEqual(printName.echo(NaN), undefined)
+    })
+
+    it('converts Infinity to undefined', () => {
+      assert.strictEqual(printName.getInfinity(), undefined)
+      assert.strictEqual(printName.echo(Infinity), undefined)
+    })
+
     it('keeps its constructor name for objects', () => {
       const buf = Buffer.from('test')
       assert.equal(printName.print(buf), 'Buffer')

spec/fixtures/api/sandbox.html

@@ -98,10 +98,8 @@
         popup.ipcRenderer.once('verified', () => {
           popup.ipcRenderer.send('child-answer')
         })
-        setTimeout(() => {
-          ipcRenderer.send('parent-ready')
-          popup.ipcRenderer.send('child-ready')
-        }, 50)
+        ipcRenderer.send('parent-ready')
+        popup.ipcRenderer.send('child-ready')
       }
     }
 

spec/fixtures/module/print_name.js

@@ -26,3 +26,11 @@ exports.typedArray = function (type, values) {
   }
   return array
 }
+
+exports.getNaN = function () {
+  return NaN
+}
+
+exports.getInfinity = function () {
+  return Infinity
+}