mac: Remove IsOSLion().

chrome/browser/ui/cocoa/tabs/tab_strip_drag_controller.mm

Index: chrome/browser/ui/cocoa/tabs/tab_strip_drag_controller.mm
diff --git a/chrome/browser/ui/cocoa/tabs/tab_strip_drag_controller.mm b/chrome/browser/ui/cocoa/tabs/tab_strip_drag_controller.mm
index 64b8d28893ee97d3209a072e8ae783b2d56be4f4..3d168310cbb5820ab90d3ccf9d4b9e060d6e76ba 100644
--- a/chrome/browser/ui/cocoa/tabs/tab_strip_drag_controller.mm
+++ b/chrome/browser/ui/cocoa/tabs/tab_strip_drag_controller.mm
@@ -211,13 +211,9 @@ static BOOL PointIsInsideView(NSPoint screenPoint, NSView* view) {
         // Offset the new window's drag location so that the tab will still be
         // positioned correctly beneath the mouse (being careful to convert the
         // view frame offset to screen coordinates).
-        if (base::mac::IsOSLionOrLater()) {
-          NSWindow* tabViewWindow = [[draggedTab_ tabView] window];
-          horizDragOffset_ = [tabViewWindow convertRectToScreen:
-              NSMakeRect(0.0, 0.0, tabWidthBeyondRightEdge, 1.0)].size.width;
-        } else {
-          horizDragOffset_ = tabWidthBeyondRightEdge;
-        }
+        NSWindow* tabViewWindow = [[draggedTab_ tabView] window];
+        horizDragOffset_ = [tabViewWindow convertRectToScreen:
+            NSMakeRect(0.0, 0.0, tabWidthBeyondRightEdge, 1.0)].size.width;
       }
 
       [[draggedTab_ tabView] setFrameOrigin:newTabFrame.origin];