Implement top controls show/hide functionality for main thread scrolling

Source/core/frame/FrameHost.cpp

Index: Source/core/frame/FrameHost.cpp
diff --git a/Source/core/frame/FrameHost.cpp b/Source/core/frame/FrameHost.cpp
index bcc05520a5a54b4fddfa488a3da01c7e96b76579..11289a15ddc6cde436f17c3387452d24149d93e6 100644
--- a/Source/core/frame/FrameHost.cpp
+++ b/Source/core/frame/FrameHost.cpp
@@ -32,6 +32,7 @@
 #include "core/frame/FrameHost.h"
 
 #include "core/frame/EventHandlerRegistry.h"
+#include "core/frame/TopControls.h"
 #include "core/inspector/ConsoleMessageStorage.h"
 #include "core/inspector/InspectorController.h"
 #include "core/page/Chrome.h"
@@ -47,6 +48,7 @@ PassOwnPtrWillBeRawPtr<FrameHost> FrameHost::create(Page& page)
 
 FrameHost::FrameHost(Page& page)
     : m_page(&page)
+    , m_topControls(TopControls::create(*this))
     , m_pinchViewport(PinchViewport::create(*this))
     , m_eventHandlerRegistry(adoptPtrWillBeNoop(new EventHandlerRegistry(*this)))
     , m_consoleMessageStorage(ConsoleMessageStorage::create())
@@ -84,6 +86,11 @@ float FrameHost::deviceScaleFactor() const
     return m_page->deviceScaleFactor();
 }
 
+TopControls& FrameHost::topControls() const
+{
+    return *m_topControls;
+}
+
 PinchViewport& FrameHost::pinchViewport() const
 {
     return *m_pinchViewport;
@@ -102,6 +109,7 @@ ConsoleMessageStorage& FrameHost::consoleMessageStorage() const
 void FrameHost::trace(Visitor* visitor)
 {
     visitor->trace(m_page);
+    visitor->trace(m_topControls);
     visitor->trace(m_pinchViewport);
     visitor->trace(m_eventHandlerRegistry);
     visitor->trace(m_consoleMessageStorage);