* Output of `node_modules/.bin/electron --version`: v3.0.2
* Operating System (Platform and Version): Windows 10 Pro 17134
* Output of `node_modules/.bin/electron --version` on last known working Electron version (if applicable): v1.6.15

**Expected Behavior**
Reloading (Ctrl R) a `BrowserWindow` with `backgroundColor` set should display that background color until the page begins to load.

**Actual behavior**
Reloading (Ctrl R) a `BrowserWindow` with `backgroundColor` set displays white until the page begins to load.

**To Reproduce**
I've reproduced the issue in electron-quick-start by:
* Adding ` style="background-color: transparent;"` to `index.html`'s `body` tag (pedantic, I know)
* Adding `backgroundColor: '#ffff0000', ` to `main.js`'s `BrowserWindow` options
* Alternatively, clone my fork of electron-quick-start:
```sh
$ git clone https://github.com/adill/electron-quick-start.git -b background-color-reload
$ npm install
$ npm start
```
1. Notice the red background color on the page (transparent body is showing through to the opaque red background.)
2. Reload (Ctrl R)
3. Notice the background color is now white

atom/renderer/renderer_client_base.cc
content::RenderFrame* render_frame) {
  
  render_frame->GetWebFrame()->ExecuteScript(blink::WebScriptSource("void 0"));
}
std::unique_ptr<blink::WebSpeechSynthesizer>
RendererClientBase::OverrideSpeechSynthesizer(
    blink::WebSpeechSynthesizerClient* client) {
#if BUILDFLAG(ENABLE_TTS)
  return std::make_unique<TtsDispatcher>(client);
#else
  return nullptr;
#endif
}
bool RendererClientBase::OverrideCreatePlugin(
    content::RenderFrame* render_frame,
    const blink::WebPluginParams& params,
    blink::WebPlugin** plugin) {
  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
  if (params.mime_type.Utf8() == content::kBrowserPluginMimeType ||
#if BUILDFLAG(ENABLE_PDF_VIEWER)
      params.mime_type.Utf8() == kPdfPluginMimeType ||
#endif  
      command_line->HasSwitch(switches::kEnablePlugins))
    return false;
  *plugin = nullptr;
  return true;
}
void RendererClientBase::AddSupportedKeySystems(