Adds scroll position/scale emulation to DevTools.

third_party/WebKit/Source/core/frame/ScrollAndScaleEmulator.h

Index: third_party/WebKit/Source/core/frame/ScrollAndScaleEmulator.h
diff --git a/third_party/WebKit/Source/core/frame/ScrollAndScaleEmulator.h b/third_party/WebKit/Source/core/frame/ScrollAndScaleEmulator.h
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+/*
+ * Copyright (C) 2016 Google Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef ScrollAndScaleEmulator_h
+#define ScrollAndScaleEmulator_h
+
+#include "core/CoreExport.h"
+#include "platform/geometry/DoublePoint.h"
+#include "wtf/Noncopyable.h"
+#include "wtf/RefCounted.h"
+
+namespace blink {
+
+class Page;
+struct PageScaleConstraints;
+
+// Overrides the scroll positions of frame and visual viewport and the page
+// scale with fixed values.
+//
+// Scroll position overrides are enforced within VisualViewport and FrameView
+// by manipulating their minimum/maximum scroll positions. The override is then
+// applied when the scroll position is clamped to these min/max values.
+//
+// Similarly, the scale override is enforced through setting custom user-agent
+// PageScaleConstraints in WebViewImpl.
+class CORE_EXPORT ScrollAndScaleEmulator final : public RefCounted<ScrollAndScaleEmulator> {
+    WTF_MAKE_NONCOPYABLE(ScrollAndScaleEmulator);
+public:
+    static PassRefPtr<ScrollAndScaleEmulator> create();
+
+    virtual ~ScrollAndScaleEmulator() {}
+
+    // Update override values. Returns |true| if values changed.
+    bool update(const IntPoint& framePosition, const DoublePoint& visualViewportPosition, float pageScale);
+
+    IntPoint applyFramePositionOverride(const IntPoint& position, const IntPoint& minimum, const IntPoint& maximum);
+    DoublePoint applyVisualViewportPositionOverride(const DoublePoint& position, const DoublePoint& minimum, const DoublePoint& maximum);
+    PageScaleConstraints pageScaleConstraints();
+
+    void disableThreadedScrolling(Page*);
+    void restoreThreadedScrolling(Page*);
+
+private:
+    ScrollAndScaleEmulator();
+
+    template <typename Point>
+    Point applyPositionOverride(const Point& position, const Point& minimum, const Point& maximum, const Point& override);
+
+    // Scroll position of frame. |x < 0| or |y < 0| disables the override for the respective coordinate.
+    IntPoint m_framePosition;
+
+    // Scroll position of visual viewport. |x < 0| or |y < 0| disables the override for the respective coordinate.
+    DoublePoint m_visualViewportPosition;
+
+    // Simulates visual viewport pinch zoom. |pageScale == 0| disables the override.
+    double m_pageScale;
+
+    bool m_threadedScrollingEnabledByDefault;
+};
+
+} // namespace blink
+
+#endif // ScrollAndScaleEmulator_h