Adjust maximum scroll bounds on FrameView to account for top controls. (Blink-side)

Source/core/frame/FrameView.cpp

Index: Source/core/frame/FrameView.cpp
diff --git a/Source/core/frame/FrameView.cpp b/Source/core/frame/FrameView.cpp
index 0aead4777869975461aa32155082b51948005ade..0a2af2873d6521af1cd299a362c1391f7b2d948a 100644
--- a/Source/core/frame/FrameView.cpp
+++ b/Source/core/frame/FrameView.cpp
@@ -118,6 +118,7 @@ FrameView::FrameView(LocalFrame* frame)
     , m_layoutSizeFixedToFrameSize(true)
     , m_didScrollTimer(this, &FrameView::didScrollTimerFired)
     , m_needsUpdateWidgetPositions(false)
+    , m_topControlsViewportAdjustment(0)
 {
     ASSERT(m_frame);
     init();
@@ -2982,4 +2983,16 @@ void FrameView::willRemoveScrollbar(Scrollbar* scrollbar, ScrollbarOrientation o
     }
 }
 
+void FrameView::setTopControlsViewportAdjustment(int adjustment)
+{
+    m_topControlsViewportAdjustment = adjustment;
+}
+
+IntPoint FrameView::maximumScrollPosition() const
+{
+    IntPoint max = ScrollView::maximumScrollPosition();
+    max.move(0, m_topControlsViewportAdjustment / visibleContentScaleFactor());
+    return max;
+}
+
 } // namespace blink