Export the tablet mode checking function from base.

base/win/win_util.cc

Index: base/win/win_util.cc
diff --git a/base/win/win_util.cc b/base/win/win_util.cc
index 87bde159cd5ac0420d3043cd87797cacfaf3f133..e9f817fc6ed8e7386f2b438dfff70b20bf86e3b4 100644
--- a/base/win/win_util.cc
+++ b/base/win/win_util.cc
@@ -114,12 +114,14 @@ POWER_PLATFORM_ROLE GetPlatformRole() {
   return PowerDeterminePlatformRoleEx(POWER_PLATFORM_ROLE_V2);
 }
 
+}  // namespace
+
 // Uses the Windows 10 WRL API's to query the current system state. The API's
 // we are using in the function below are supported in Win32 apps as per msdn.
 // It looks like the API implementation is buggy at least on Surface 4 causing
 // it to always return UserInteractionMode_Touch which as per documentation
 // indicates tablet mode.
-bool IsWindows10TabletDevice() {
+bool IsWindows10TabletMode(HWND hwnd) {
   if (GetVersion() < VERSION_WIN10)
     return false;
 
@@ -178,7 +180,7 @@ bool IsWindows10TabletDevice() {
   // Avoid using GetForegroundWindow here and pass in the HWND of the window
   // intiating the request to display the keyboard.
   hr = view_settings_interop->GetForWindow(
-      ::GetForegroundWindow(),
+      hwnd,
       __uuidof(ABI::Windows::UI::ViewManagement::IUIViewSettings),
       view_settings.ReceiveVoid());
   if (FAILED(hr))
@@ -190,8 +192,6 @@ bool IsWindows10TabletDevice() {
   return mode == ABI::Windows::UI::ViewManagement::UserInteractionMode_Touch;
 }
 
-}  // namespace
-
 // Returns true if a physical keyboard is detected on Windows 8 and up.
 // Uses the Setup APIs to enumerate the attached keyboards and returns true
 // if the keyboard count is 1 or more.. While this will work in most cases
@@ -475,7 +475,7 @@ bool IsTabletDevice(std::string* reason) {
     return false;
   }
 
-  if (IsWindows10TabletDevice())
+  if (IsWindows10TabletMode(::GetForegroundWindow()))
     return true;
 
   if (GetSystemMetrics(SM_MAXIMUMTOUCHES) == 0) {