Enable hidpi on Linux, refactor a bit on Windows to share

ui/views/corewm/tooltip_win.cc

Index: ui/views/corewm/tooltip_win.cc
diff --git a/ui/views/corewm/tooltip_win.cc b/ui/views/corewm/tooltip_win.cc
index 4d2a4badb0ebd4635c25a92783b8b71abd8c2014..67aa1e2e21e4d40762c6b7e0def9518c77d891f8 100644
--- a/ui/views/corewm/tooltip_win.cc
+++ b/ui/views/corewm/tooltip_win.cc
@@ -10,9 +10,9 @@
 #include "base/i18n/rtl.h"
 #include "base/logging.h"
 #include "ui/base/l10n/l10n_util_win.h"
+#include "ui/gfx/dpi.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/screen.h"
-#include "ui/gfx/win/dpi.h"
 #include "ui/views/corewm/cursor_height_provider_win.h"
 
 namespace views {
@@ -78,7 +78,7 @@ bool TooltipWin::EnsureTooltipWindow() {
 
 void TooltipWin::PositionTooltip() {
   // This code only runs for non-metro, so GetNativeScreen() is fine.
-  gfx::Point screen_point = gfx::win::DIPToScreenPoint(location_);
+  gfx::Point screen_point = gfx::DIPToScreenPoint(location_);
   const int cursoroffset = GetCurrentCursorVisibleHeight();
   screen_point.Offset(0, cursoroffset);
 
@@ -90,7 +90,7 @@ void TooltipWin::PositionTooltip() {
       gfx::Screen::GetNativeScreen()->GetDisplayNearestPoint(screen_point));
 
   gfx::Rect tooltip_bounds(screen_point, size);
-  tooltip_bounds.AdjustToFit(gfx::win::DIPToScreenRect(display.work_area()));
+  tooltip_bounds.AdjustToFit(gfx::DIPToScreenRect(display.work_area()));
   SetWindowPos(tooltip_hwnd_, NULL, tooltip_bounds.x(), tooltip_bounds.y(), 0,
                0, SWP_NOSIZE | SWP_NOZORDER | SWP_NOACTIVATE);
 }
@@ -117,7 +117,7 @@ void TooltipWin::SetText(aura::Window* window,
               reinterpret_cast<LPARAM>(&toolinfo_));
 
   // This code only runs for non-metro, so GetNativeScreen() is fine.
-  const gfx::Point screen_point = gfx::win::DIPToScreenPoint(location_);
+  const gfx::Point screen_point = gfx::DIPToScreenPoint(location_);
   gfx::Display display(
       gfx::Screen::GetNativeScreen()->GetDisplayNearestPoint(screen_point));
   const gfx::Rect monitor_bounds = display.bounds();