headless: Implement screenshot capturing

headless/lib/browser/headless_browser_impl.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "headless/lib/browser/headless_browser_impl.h"
 
+#include <vector>
+
 #include "base/memory/ptr_util.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "content/public/app/content_main.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/web_contents.h"
 #include "headless/lib/browser/headless_browser_context.h"
 #include "headless/lib/browser/headless_browser_main_parts.h"
 #include "headless/lib/browser/headless_web_contents_impl.h"
 #include "headless/lib/browser/headless_window_tree_client.h"
 #include "headless/lib/headless_content_main_delegate.h"
@@ skipping 27 matching lines @@
 
   return RegisterWebContents(std::move(headless_web_contents));
 }
 
 scoped_refptr<base::SingleThreadTaskRunner>
 HeadlessBrowserImpl::BrowserMainThread() const {
   return content::BrowserThread::GetMessageLoopProxyForThread(
       content::BrowserThread::UI);
 }
 
+scoped_refptr<base::SingleThreadTaskRunner>
+HeadlessBrowserImpl::BrowserFileThread() const {
+  return content::BrowserThread::GetMessageLoopProxyForThread(
+      content::BrowserThread::FILE);
+}
+
 void HeadlessBrowserImpl::Shutdown() {
   DCHECK(BrowserMainThread()->BelongsToCurrentThread());
   BrowserMainThread()->PostTask(FROM_HERE,
                                 base::MessageLoop::QuitWhenIdleClosure());
 }
 
 std::vector<HeadlessWebContents*> HeadlessBrowserImpl::GetAllWebContents() {
   std::vector<HeadlessWebContents*> result;
   result.reserve(web_contents_.size());
 
@@ skipping 16 matching lines @@
 }
 
 void HeadlessBrowserImpl::set_browser_main_parts(
     HeadlessBrowserMainParts* browser_main_parts) {
   DCHECK(!browser_main_parts_);
   browser_main_parts_ = browser_main_parts;
 }
 
 void HeadlessBrowserImpl::RunOnStartCallback() {
   DCHECK(aura::Env::GetInstance());
-  window_tree_host_.reset(aura::WindowTreeHost::Create(gfx::Rect()));
+  // TODO(eseckler): allow configuration of window (viewport) size by embedder.
+  const gfx::Size kDefaultSize(800, 600);
+  window_tree_host_.reset(
+      aura::WindowTreeHost::Create(gfx::Rect(kDefaultSize)));
   window_tree_host_->InitHost();
 
   window_tree_client_.reset(
       new HeadlessWindowTreeClient(window_tree_host_->window()));
 
   on_start_callback_.Run(this);
   on_start_callback_ = base::Callback<void(HeadlessBrowser*)>();
 }
 
 HeadlessWebContentsImpl* HeadlessBrowserImpl::RegisterWebContents(
@@ skipping 27 matching lines @@
   DCHECK(!options.message_pump);
 
   std::unique_ptr<HeadlessBrowserImpl> browser(
       new HeadlessBrowserImpl(on_browser_start_callback, std::move(options)));
   headless::HeadlessContentMainDelegate delegate(std::move(browser));
   params.delegate = &delegate;
   return content::ContentMain(params);
 }
 
 }  // namespace headless