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..52578d0d9e58724e23844074f5770d4cf86276b5 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(float adjustment)
+{
+    m_topControlsViewportAdjustment = adjustment;
+}
+
+IntPoint FrameView::maximumScrollPosition() const
+{
+    IntPoint max = ScrollView::maximumScrollPosition();
+    max.move(0, m_topControlsViewportAdjustment / visibleContentScaleFactor());

[leviw_travelin_and_unemployed, 2014/09/10 20:15:51]

Don't you want to ceil this value? If so, I'd expect a test that ensures we
don't lose a pixel.

[bokan, 2014/09/15 20:30:19]

I think we want to floor in this case (since we ceil the visibleSize, we should
floor anything we take away from it), but I'll admit this isn't terribly clear.
I've rewritten it to essentially the following:

max = contentHeight - ceil((visibleHeight-adjustment)/scale)

Which is what happens on the CC side. Also added to the test to check the
fractional pixel case.

+    return max;
+}
+
 } // namespace blink