headless: Implement screenshot capturing

headless/public/headless_browser.h

 // 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.
 
 #ifndef HEADLESS_PUBLIC_HEADLESS_BROWSER_H_
 #define HEADLESS_PUBLIC_HEADLESS_BROWSER_H_
 
 #include <memory>
 #include <string>
 #include <unordered_map>
+#include <vector>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "headless/public/headless_export.h"
 #include "net/base/host_port_pair.h"
 #include "net/base/ip_endpoint.h"
 #include "net/url_request/url_request_job_factory.h"
 
 namespace base {
@@ skipping 23 matching lines @@
   // HeadlessWebContents::Observer::DevToolsTargetReady.
   virtual HeadlessWebContents* CreateWebContents(const GURL& initial_url,
                                                  const gfx::Size& size) = 0;
 
   virtual std::vector<HeadlessWebContents*> GetAllWebContents() = 0;
 
   // Returns a task runner for submitting work to the browser main thread.
   virtual scoped_refptr<base::SingleThreadTaskRunner> BrowserMainThread()
       const = 0;
 
+  // Returns a task runner for submitting work to the browser file thread.
+  virtual scoped_refptr<base::SingleThreadTaskRunner> BrowserFileThread()
+      const = 0;
+
   // Requests browser to stop as soon as possible. |Run| will return as soon as
   // browser stops.
   virtual void Shutdown() = 0;
 
  protected:
   HeadlessBrowser() {}
   virtual ~HeadlessBrowser() {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(HeadlessBrowser);
@@ skipping 76 matching lines @@
 // |on_browser_start_callback| callback. Note that since this function executes
 // the main loop, it will only return after HeadlessBrowser::Shutdown() is
 // called, returning the exit code for the process.
 int HeadlessBrowserMain(
     HeadlessBrowser::Options options,
     const base::Callback<void(HeadlessBrowser*)>& on_browser_start_callback);
 
 }  // namespace headless
 
 #endif  // HEADLESS_PUBLIC_HEADLESS_BROWSER_H_