[Aura] Always use IMM32 on desktop Chrome (non-Ash mode)

This CL partially reverts r194205, which aimed to support
IME for Ash. With this partial rollback, we can assume
that all the instances of Aura-Win Chrome running in desktop
use IMM32 regardless of the OS version.

Given that Ash IME support is not functional yet, there is
no strong reason to force TSF only on Win8+. Actually our
IMM32 implemenation is more robust than that of TSF. This
way should lower the risk of successful launch of Aura for
Windows in M31.

BUG=164964
TEST=manually confirmed that we can use IME with Win8 Aura build

Review URL: https://chromiumcodereview.appspot.com/23875022

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@223589 0039d316-1c4b-4281-b951-d872f2087c98

base/win/metro.cc

@@ -71,10 +71,6 @@ bool IsProcessImmersive(HANDLE process) {
 }
 
 bool IsTSFAwareRequired() {
-#if defined(USE_AURA)
-  if (base::win::GetVersion() >= base::win::VERSION_WIN8)
-    return true;
-#endif
   // Although this function is equal to IsMetroProcess at this moment,
   // Chrome for Win7 and Vista may support TSF in the future.
   return g_should_tsf_aware_required || IsMetroProcess();