Use IMM32 instead of TSF on Win7.

On Windows 7, there are many IMM32-based IMEs are relying on IMM32
support. We should continue supporting those legacy IMEs on Win7. We
should disable TSF on Win7 and use IMM32. All other Windows platforms
are not affected.

Bug: 963558
Change-Id: I8f77afbdb734c355f4393880e80fafd98e25ae88
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1613974Reviewed-by: Yohei Yukawa <yukawa@chromium.org>
Commit-Queue: Siye Liu <siliu@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#660261}

ui/base/ime/init/input_method_factory.cc

@@ -6,6 +6,7 @@
 
 #include "base/command_line.h"
 #include "base/memory/ptr_util.h"
+#include "base/win/windows_version.h"
 #include "build/build_config.h"
 #include "ui/base/ime/mock_input_method.h"
 #include "ui/base/ui_base_features.h"
@@ -59,8 +60,10 @@ std::unique_ptr<InputMethod> CreateInputMethod(
 #if defined(OS_CHROMEOS)
   return std::make_unique<InputMethodChromeOS>(delegate);
 #elif defined(OS_WIN)
-  if (base::FeatureList::IsEnabled(features::kTSFImeSupport))
+  if (base::FeatureList::IsEnabled(features::kTSFImeSupport) &&
+      base::win::GetVersion() > base::win::Version::WIN7) {
     return std::make_unique<InputMethodWinTSF>(delegate, widget);
+  }
   return std::make_unique<InputMethodWinImm32>(delegate, widget);
 #elif defined(OS_MACOSX)
   return std::make_unique<InputMethodMac>(delegate);