Reland of Decouple ScreenMetricsEmulator From RenderWidget

> Original issue's description:
> > Decouple ScreenMetricsEmulator From RenderWidget
> >
> > This is part of the ongoing effort to thin down RenderWidget to be just IPC transport.
> > Started in http://crrev.com/1599583002
> >
> > BUG=577321

TBR=dgozman@chromium.org,fsamuel@chromium.org,jam@chromium.org,pfeldman@chromium.org

BUG=577321

Review URL: https://codereview.chromium.org/1697263008

Cr-Commit-Position: refs/heads/master@{#375977}

1 files changed, 88 insertions, 0 deletions

diff --git a/content/renderer/devtools/render_widget_screen_metrics_emulator.h b/content/renderer/devtools/render_widget_screen_metrics_emulator.h
new file mode 100644
index 0000000..8288dfa
--- /dev/null
+++ b/content/renderer/devtools/render_widget_screen_metrics_emulator.h
@@ -0,0 +1,88 @@
+// 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 CONTENT_RENDERER_DEVTOOLS_RENDER_WIDGET_SCREEN_METRICS_EMULATOR_H_
+#define CONTENT_RENDERER_DEVTOOLS_RENDER_WIDGET_SCREEN_METRICS_EMULATOR_H_
+
+#include "base/memory/scoped_ptr.h"
+#include "content/common/resize_params.h"
+#include "third_party/WebKit/public/web/WebDeviceEmulationParams.h"
+
+namespace gfx {
+class PointF;
+class Rect;
+}
+
+namespace content {
+
+class RenderWidgetScreenMetricsEmulatorDelegate;
+struct ContextMenuParams;
+
+// RenderWidgetScreenMetricsEmulator class manages screen emulation inside a
+// RenderWidget. This includes resizing, placing view on the screen at desired
+// position, changing device scale factor, and scaling down the whole
+// widget if required to fit into the browser window.
+class RenderWidgetScreenMetricsEmulator {
+ public:
+  RenderWidgetScreenMetricsEmulator(
+      RenderWidgetScreenMetricsEmulatorDelegate* delegate,
+      const blink::WebDeviceEmulationParams& params,
+      const ResizeParams& resize_params,
+      const gfx::Rect& view_screen_rect,
+      const gfx::Rect& window_screen_rect);
+  virtual ~RenderWidgetScreenMetricsEmulator();
+
+  // Scale and offset used to convert between host coordinates
+  // and webwidget coordinates.
+  const gfx::Size& original_size() const {
+    return original_resize_params_.new_size;
+  }
+
+  float scale() const { return scale_; }
+  const gfx::PointF& offset() const { return offset_; }
+  const gfx::Rect& applied_widget_rect() const { return applied_widget_rect_; }
+  const blink::WebScreenInfo& original_screen_info() const {
+    return original_resize_params_.screen_info;
+  }
+  const gfx::Rect& original_screen_rect() const {
+    return original_view_screen_rect_;
+  }
+
+  void ChangeEmulationParams(const blink::WebDeviceEmulationParams& params);
+
+  // The following methods alter handlers' behavior for messages related to
+  // widget size and position.
+  void OnResize(const ResizeParams& params);
+  void OnUpdateScreenRects(const gfx::Rect& view_screen_rect,
+                           const gfx::Rect& window_screen_rect);
+  void OnShowContextMenu(ContextMenuParams* params);
+  gfx::Rect AdjustValidationMessageAnchor(const gfx::Rect& anchor);
+
+ private:
+  // Apply original_resize_params_
+  void Apply();
+
+  RenderWidgetScreenMetricsEmulatorDelegate* const delegate_;
+
+  // Parameters as passed by RenderWidget::EnableScreenMetricsEmulation.
+  blink::WebDeviceEmulationParams emulation_params_;
+
+  // The computed scale and offset used to fit widget into browser window.
+  float scale_;
+  gfx::PointF offset_;
+
+  // Widget rect as passed to webwidget.
+  gfx::Rect applied_widget_rect_;
+
+  // Original values to restore back after emulation ends.
+  ResizeParams original_resize_params_;
+  gfx::Rect original_view_screen_rect_;
+  gfx::Rect original_window_screen_rect_;
+
+  DISALLOW_COPY_AND_ASSIGN(RenderWidgetScreenMetricsEmulator);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_RENDERER_DEVTOOLS_RENDER_WIDGET_SCREEN_METRICS_EMULATOR_H_