Refactor the IsKeyboardPresentOnSlate function.

base/win/win_util.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // =============================================================================
 // PLEASE READ
 //
 // In general, you should not be adding stuff to this file.
 //
 // - If your thing is only used in one place, just put it in a reasonable
@@ skipping 104 matching lines @@
 // Note that not all mechanisms for terminating the process are covered by
 // this. In particular, TerminateProcess() is not caught.
 BASE_EXPORT void SetShouldCrashOnProcessDetach(bool crash);
 BASE_EXPORT bool ShouldCrashOnProcessDetach();
 
 // Adjusts the abort behavior so that crash reports can be generated when the
 // process is aborted.
 BASE_EXPORT void SetAbortBehaviorForCrashReporting();
 
 // A tablet is a device that is touch enabled and also is being used
-// "like a tablet".  This is used primarily for metrics in order to gain some
-// insight into how users use Chrome.
-BASE_EXPORT bool IsTabletDevice();
+// "like a tablet". This is used by the following:-
+// 1. Metrics:- To gain insight into how users use Chrome.
+// 2. Physical keyboard presence :- If a device is in tablet mode, it means
+//    that there is no physical keyboard attached.
+// This function optionally sets the |reason| parameter to determine as to why
+// or why not a device was deemed to be a tablet.
+// Returns true if the device is in tablet mode.
+BASE_EXPORT bool IsTabletDevice(std::string* reason);
 
 // A slate is a touch device that may have a keyboard attached. This function
 // returns true if a keyboard is attached and optionally will set the reason
 // parameter to the detection method that was used to detect the keyboard.
 BASE_EXPORT bool IsKeyboardPresentOnSlate(std::string* reason);
 
 // Get the size of a struct up to and including the specified member.
 // This is necessary to set compatible struct sizes for different versions
 // of certain Windows APIs (e.g. SystemParametersInfo).
 #define SIZEOF_STRUCT_WITH_SPECIFIED_LAST_MEMBER(struct_name, member) \
@@ skipping 26 matching lines @@
 // CreateWindow and CreateDC. Windows 8 and above allow the kernel component
 // of these calls to be disabled which can cause undefined behaviour such as
 // crashes. This function can be used to guard areas of code using these calls
 // and provide a fallback path if necessary.
 BASE_EXPORT bool IsUser32AndGdi32Available();
 
 }  // namespace win
 }  // namespace base
 
 #endif  // BASE_WIN_WIN_UTIL_H_