Implement window management devtools commands for headless.

headless/lib/browser/headless_web_contents_impl.cc

Index: headless/lib/browser/headless_web_contents_impl.cc
diff --git a/headless/lib/browser/headless_web_contents_impl.cc b/headless/lib/browser/headless_web_contents_impl.cc
index 36015b66c4cf675fbb05f33f643018e63daddb68..1d0598b6737d3f3483eef8eab71801affb25d5f9 100644
--- a/headless/lib/browser/headless_web_contents_impl.cc
+++ b/headless/lib/browser/headless_web_contents_impl.cc
@@ -173,7 +173,9 @@ std::unique_ptr<HeadlessWebContentsImpl> HeadlessWebContentsImpl::Create(
   }
 
   headless_web_contents->mojo_services_ = std::move(builder->mojo_services_);
-  headless_web_contents->InitializeScreen(builder->window_size_);
+  headless_web_contents->InitializeScreen(
+      builder->window_size_,
+      builder->browser_context_->options()->screen_size());
   if (!headless_web_contents->OpenURL(builder->initial_url_))
     return nullptr;
   return headless_web_contents;
@@ -191,8 +193,11 @@ HeadlessWebContentsImpl::CreateFromWebContents(
   return headless_web_contents;
 }
 
-void HeadlessWebContentsImpl::InitializeScreen(const gfx::Size& initial_size) {
-  browser()->PlatformInitializeWebContents(initial_size, this);
+void HeadlessWebContentsImpl::InitializeScreen(
+    const gfx::Size& initial_window_size,
+    const gfx::Size& screen_size) {
+  browser()->PlatformInitializeWebContents(initial_window_size, screen_size,
+                                           this);
 }
 
 HeadlessWebContentsImpl::HeadlessWebContentsImpl(