Adds DevTools commands for forced viewport override.

third_party/WebKit/Source/web/DevToolsEmulator.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 DevToolsEmulator_h
 #define DevToolsEmulator_h
 
 #include "platform/heap/Handle.h"
 #include "public/platform/PointerProperties.h"
+#include "public/platform/WebFloatPoint.h"
 #include "public/platform/WebViewportStyle.h"
 #include "public/web/WebDeviceEmulationParams.h"
+#include "web/WebExport.h"
 #include "wtf/Forward.h"
+#include "wtf/Optional.h"
 #include <memory>
 
 namespace blink {
 
 class InspectorEmulationAgent;
 class IntPoint;
+class IntRect;
+class TransformationMatrix;
 class WebInputEvent;
 class WebViewImpl;
 
-class DevToolsEmulator final : public GarbageCollectedFinalized<DevToolsEmulator> {
+class WEB_EXPORT DevToolsEmulator final : public GarbageCollectedFinalized<DevToolsEmulator> {
 public:
     ~DevToolsEmulator();
     static DevToolsEmulator* create(WebViewImpl*);
     DECLARE_TRACE();
 
     // Settings overrides.
     void setTextAutosizingEnabled(bool);
     void setDeviceScaleAdjustment(float);
     void setPreferCompositingToLCDTextEnabled(bool);
     void setViewportStyle(WebViewportStyle);
     void setPluginsEnabled(bool);
     void setScriptEnabled(bool);
     void setDoubleTapToZoomEnabled(bool);
     bool doubleTapToZoomEnabled() const;
     void setAvailablePointerTypes(int);
     void setPrimaryPointerType(PointerType);
     void setAvailableHoverTypes(int);
     void setPrimaryHoverType(HoverType);
     void setMainFrameResizesAreOrientationChanges(bool);
     bool mainFrameResizesAreOrientationChanges() const;
 
     // Emulation.
     void enableDeviceEmulation(const WebDeviceEmulationParams&);
     void disableDeviceEmulation();
+    void forceViewport(const WebFloatPoint& position, float scale);

[chrishtr, 2016/08/22 22:00:42]

Scale after position, or before? Units for position?

[Eric Seckler, 2016/08/23 09:32:19]

Units are documented in the corresponding protocol message, I added a comment
here as well. Since position is given in CSS pixels (rather than DIPs), I don't
think we need an additional comment that scale is applied after positioning.

+    void resetViewport();
     bool resizeIsDeviceSizeChange();
     void setTouchEventEmulationEnabled(bool);
     bool handleInputEvent(const WebInputEvent&);
     void setScriptExecutionDisabled(bool);
 
+    // Notify the DevToolsEmulator about a scroll or scale change of the main
+    // frame. Updates the transform for a viewport override.
+    void mainFrameScrollOrScaleChanged();
+
+    // Returns a custom visible content rect if a viewport override is active.
+    // This ensures that all content inside the forced viewport is painted.
+    WTF::Optional<IntRect> visibleContentRectForPainting() const;
+
 private:
     explicit DevToolsEmulator(WebViewImpl*);
 
     void enableMobileEmulation();
     void disableMobileEmulation();
 
+    void applyDeviceEmulationTransform(TransformationMatrix*);
+    void applyViewportOverride(TransformationMatrix*);
+    void updateRootLayerTransform();
+
     WebViewImpl* m_webViewImpl;
 
     bool m_deviceMetricsEnabled;
     bool m_emulateMobileEnabled;
     WebDeviceEmulationParams m_emulationParams;
 
+    struct ViewportOverride {
+        WebFloatPoint position;
+        double scale;
+        bool originalVisualViewportMasking;
+    };
+    WTF::Optional<ViewportOverride> m_viewportOverride;
+
     bool m_isOverlayScrollbarsEnabled;
     bool m_isOrientationEventEnabled;
     bool m_isMobileLayoutThemeEnabled;
     float m_originalDefaultMinimumPageScaleFactor;
     float m_originalDefaultMaximumPageScaleFactor;
     bool m_embedderTextAutosizingEnabled;
     float m_embedderDeviceScaleAdjustment;
     bool m_embedderPreferCompositingToLCDTextEnabled;
     WebViewportStyle m_embedderViewportStyle;
     bool m_embedderPluginsEnabled;
@@ skipping 12 matching lines @@
     std::unique_ptr<IntPoint> m_lastPinchAnchorCss;
     std::unique_ptr<IntPoint> m_lastPinchAnchorDip;
 
     bool m_embedderScriptEnabled;
     bool m_scriptExecutionDisabled;
 };
 
 } // namespace blink
 
 #endif