Revert r156303 as non-Aura Metro mode is gone

base/win/metro.h

Index: base/win/metro.h
diff --git a/base/win/metro.h b/base/win/metro.h
index b2208fcb49c06c441fcb377fd65f1135a6d50a91..04bab1ef832fe849577086e9181b22b4c480f5b8 100644
--- a/base/win/metro.h
+++ b/base/win/metro.h
@@ -80,13 +80,6 @@ BASE_EXPORT bool IsProcessImmersive(HANDLE process);
 // and browser must be TSF-aware.
 BASE_EXPORT bool IsTSFAwareRequired();
 
-// Sets browser to use Text Services Framework (TSF) regardless of process
-// status. On Windows 8, this function also disables CUAS (Cicero Unaware
-// Application Support) to emulate Windows Metro mode in terms of IME
-// functionality. This should be beneficial in QA process because on can test
-// IME functionality in Windows 8 desktop mode.
-BASE_EXPORT void SetForceToUseTSF();
-
 // Allocates and returns the destination string via the LocalAlloc API after
 // copying the src to it.
 BASE_EXPORT wchar_t* LocalAllocAndCopyString(const string16& src);