Aura: Combine cursor support for Linux and Windows

+ Change gfx::NativeCursor to an int id on Aura.
+ Fix several cursor-related TODOs in GetCursor() methods.
+ Move X11 cursor cache into x11_util
+ Set platform-specific cursors in aura::DesktopHostWin and DesktopHostLinux

BUG=99871
TEST=manual

Review URL: http://codereview.chromium.org/8256001

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@105850 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/views/view.cc b/views/view.cc
index fc1f938..925a40f 100644
--- a/views/view.cc
+++ b/views/view.cc
@@ -727,7 +727,7 @@
 }
 
 gfx::NativeCursor View::GetCursor(const MouseEvent& event) {
-#if defined(OS_WIN)
+#if defined(OS_WIN) && !defined(USE_AURA)
   static HCURSOR arrow = LoadCursor(NULL, IDC_ARROW);
   return arrow;
 #else