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
new file mode 100644
index 0000000000000000000000000000000000000000..acbd3af842511811e2eb05090c4d4ed2a2f6b64b
--- /dev/null
+++ b/third_party/WebKit/Source/core/frame/ScrollAndScaleEmulator.h
@@ -0,0 +1,113 @@
+/*
+ * Copyright (C) 2016 Google Inc. All rights reserved.

[bokan, 2016/07/04 22:44:09]

Use shortened license block both here and in the cpp:
https://www.chromium.org/blink/coding-style#TOC-License

[Eric Seckler, 2016/07/05 16:46:51]

Done.

+ *
+ * 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 "core/frame/PageScaleConstraints.h"
+#include "platform/geometry/DoublePoint.h"
+#include "platform/geometry/IntPoint.h"
+#include "wtf/Noncopyable.h"
+#include "wtf/PassRefPtr.h"
+#include "wtf/RefCounted.h"
+
+namespace blink {
+
+class IntSize;
+class Page;
+
+// 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> {

[bokan, 2016/07/04 22:44:09]

RefCounted is deprecated. Instead, inherit from GarbageCollected and store in a
Member<T>. See RootScrollerController for an example and
https://www.chromium.org/blink/blink-gc for the nitty gritty details.

[Eric Seckler, 2016/07/05 16:46:51]

Done.

+    WTF_MAKE_NONCOPYABLE(ScrollAndScaleEmulator);
+public:
+    // Create a new emulator instance. Also disables threaded scrolling for the
+    // page while the override is in effect.
+    static PassRefPtr<ScrollAndScaleEmulator> create(Page*);
+
+    virtual ~ScrollAndScaleEmulator() {}
+
+    // Enforce new override values, notify viewports about changes.
+    void update(Page*, const IntPoint& framePosition, const DoublePoint& visualViewportPosition, float pageScale);
+
+    // Clear overrides, notify viewports about changes. Also restores threaded
+    // scrolling settings and original user-agent PageScaleConstraints.
+    void clear(Page*);
+
+    // Return main frame scroll position with active overrides for individual
+    // coordinates applied.
+    IntPoint applyFramePositionOverride(const IntPoint&);
+
+    // Return visual viewport scroll position with active overrides for
+    // individual coordinates applied.
+    DoublePoint applyVisualViewportPositionOverride(const DoublePoint&);
+
+    // Calculate and return main frame size for original PageScaleConstraints.
+    IntSize mainFrameSize(Page*, const IntSize& webViewSize);
+
+private:
+    ScrollAndScaleEmulator();
+
+    void disableThreadedScrolling(Page*);
+    void restoreThreadedScrolling(Page*);
+
+    // Return PageScaleConstraints that enforce any active page scale override.
+    // Defaults to original constraints if no override is active.
+    PageScaleConstraints pageScaleConstraints();
+
+    void setOriginalPageScaleConstraints(const PageScaleConstraints&);
+
+    template <typename Point>
+    Point applyPositionOverride(const Point& position, 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_originalThreadedScrollingEnabled;
+    PageScaleConstraints m_originalPageScaleConstraints;
+};
+
+} // namespace blink
+
+#endif // ScrollAndScaleEmulator_h