Add an UMA metric to track whether chrome is running on a tablet.

base/win/win_util.h

Index: base/win/win_util.h
diff --git a/base/win/win_util.h b/base/win/win_util.h
index 4a5c5cdb647a2b92ffac34454a19d7f1c111a0b3..1c3f0f36c75756216dbafe768d682f35a6922c91 100644
--- a/base/win/win_util.h
+++ b/base/win/win_util.h
@@ -111,6 +111,11 @@ BASE_EXPORT void SetAbortBehaviorForCrashReporting();
 // integrated multi-touch ready to use and has Windows version > Windows7.
 BASE_EXPORT bool IsTouchEnabledDevice();
 
+// 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();
+
 // 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).