headless: make initial screen/window sizes configurable.

headless/lib/browser/headless_browser_main_parts.cc

Index: headless/lib/browser/headless_browser_main_parts.cc
diff --git a/headless/lib/browser/headless_browser_main_parts.cc b/headless/lib/browser/headless_browser_main_parts.cc
index c970b7907392e9329ec43a8c69f4cf846ea9f149..ec1ae1814d760a2eb7fe88eeeb7aaf4c12204b0d 100644
--- a/headless/lib/browser/headless_browser_main_parts.cc
+++ b/headless/lib/browser/headless_browser_main_parts.cc
@@ -16,8 +16,8 @@ namespace headless {
 
 namespace {
 
-void PlatformInitialize() {
-  HeadlessScreen* screen = HeadlessScreen::Create(gfx::Size());
+void PlatformInitialize(const gfx::Size& screen_size) {
+  HeadlessScreen* screen = HeadlessScreen::Create(screen_size);
   display::Screen::SetScreenInstance(screen);
 }
 
@@ -38,7 +38,7 @@ void HeadlessBrowserMainParts::PreMainMessageLoopRun() {
     devtools_http_handler_ =
         CreateLocalDevToolsHttpHandler(browser_context_.get());
   }
-  PlatformInitialize();
+  PlatformInitialize(browser_->options()->window_size);
 }
 
 void HeadlessBrowserMainParts::PostMainMessageLoopRun() {