headless: Initial headless embedder API implementation

This patch introduces the initial headless embedder API implementation.
It allows the embedder to initialize a headless browsing environment and
to navigate to a URL.

We also add a headless shell application to demonstrate the use of the
embedder API.

Adapted from a patch by Alexander Timin <altimin@chromium.org>

BUG=546953

Review URL: https://codereview.chromium.org/1674263002

Cr-Commit-Position: refs/heads/master@{#377973}

1 files changed, 76 insertions, 0 deletions

diff --git a/headless/lib/browser/headless_screen.h b/headless/lib/browser/headless_screen.h
new file mode 100644
index 0000000..c6b6b3b
--- /dev/null
+++ b/headless/lib/browser/headless_screen.h
@@ -0,0 +1,76 @@
+// Copyright 2016 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_LIB_BROWSER_HEADLESS_SCREEN_H_
+#define HEADLESS_LIB_BROWSER_HEADLESS_SCREEN_H_
+
+#include "base/compiler_specific.h"
+#include "base/macros.h"
+#include "ui/aura/window_observer.h"
+#include "ui/gfx/display.h"
+#include "ui/gfx/screen.h"
+
+namespace gfx {
+class Insets;
+class Rect;
+class Transform;
+}
+
+namespace aura {
+class Window;
+class WindowTreeHost;
+}
+
+namespace headless {
+
+class HeadlessScreen : public gfx::Screen, public aura::WindowObserver {
+ public:
+  // Creates a gfx::Screen of the specified size. If no size is specified, then
+  // creates a 800x600 screen. |size| is in physical pixels.
+  static HeadlessScreen* Create(const gfx::Size& size);
+  ~HeadlessScreen() override;
+
+  aura::WindowTreeHost* CreateHostForPrimaryDisplay();
+
+  void SetDeviceScaleFactor(float device_scale_fator);
+  void SetDisplayRotation(gfx::Display::Rotation rotation);
+  void SetUIScale(float ui_scale);
+  void SetWorkAreaInsets(const gfx::Insets& insets);
+
+ protected:
+  gfx::Transform GetRotationTransform() const;
+  gfx::Transform GetUIScaleTransform() const;
+
+  // WindowObserver overrides:
+  void OnWindowBoundsChanged(aura::Window* window,
+                             const gfx::Rect& old_bounds,
+                             const gfx::Rect& new_bounds) override;
+  void OnWindowDestroying(aura::Window* window) override;
+
+  // gfx::Screen overrides:
+  gfx::Point GetCursorScreenPoint() override;
+  gfx::NativeWindow GetWindowUnderCursor() override;
+  gfx::NativeWindow GetWindowAtScreenPoint(const gfx::Point& point) override;
+  int GetNumDisplays() const override;
+  std::vector<gfx::Display> GetAllDisplays() const override;
+  gfx::Display GetDisplayNearestWindow(gfx::NativeView view) const override;
+  gfx::Display GetDisplayNearestPoint(const gfx::Point& point) const override;
+  gfx::Display GetDisplayMatching(const gfx::Rect& match_rect) const override;
+  gfx::Display GetPrimaryDisplay() const override;
+  void AddObserver(gfx::DisplayObserver* observer) override;
+  void RemoveObserver(gfx::DisplayObserver* observer) override;
+
+ private:
+  explicit HeadlessScreen(const gfx::Rect& screen_bounds);
+
+  aura::WindowTreeHost* host_;
+  gfx::Display display_;
+  float ui_scale_;
+
+  DISALLOW_COPY_AND_ASSIGN(HeadlessScreen);
+};
+
+}  // namespace headless
+
+#endif  // HEADLESS_LIB_BROWSER_HEADLESS_SCREEN_H_