Add functionality to the GCAPI to detect when Chrome was last run.

chrome/installer/gcapi/gcapi.h

Index: chrome/installer/gcapi/gcapi.h
===================================================================
--- chrome/installer/gcapi/gcapi.h	(revision 108839)
+++ chrome/installer/gcapi/gcapi.h	(working copy)
@@ -1,4 +1,4 @@
-// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
+// Copyright (c) 2011 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.
 
@@ -27,7 +27,7 @@
 // set the flag even if Chrome can be offered.  If passed TRUE, this method
 // will set the flag only if Chrome can be offered.
 DLLEXPORT BOOL __stdcall GoogleChromeCompatibilityCheck(BOOL set_flag,
-                                                        DWORD *reasons);
+                                                        DWORD* reasons);
 
 // This function launches Google Chrome after a successful install. Make
 // sure COM library is NOT initalized before you call this function (so if
@@ -45,10 +45,19 @@
                                                           int width,
                                                           int height);
 
+// This function returns the number of days since Google Chrome was last run by
+// the current user. If both user-level and machine-wide installations are
+// present on the system, it will return the lowest last-run-days count of
+// the two.
+// Returns -1 if Chrome is not installed or we are otherwise unable to determine
+// how long since Chrome was last launched.
+DLLEXPORT int __stdcall GoogleChromeDaysSinceLastRun();
+
 // Funtion pointer type declarations to use with GetProcAddress.
-typedef BOOL (__stdcall * GCCC_CompatibilityCheck)(BOOL, DWORD *);
-typedef BOOL (__stdcall * GCCC_LaunchGC)(HANDLE *);
-typedef BOOL (__stdcall * GCCC_LaunchGCWithDimensions)(int, int, int, int);
+typedef BOOL (__stdcall *GCCC_CompatibilityCheck)(BOOL, DWORD *);
+typedef BOOL (__stdcall *GCCC_LaunchGC)(HANDLE *);
+typedef BOOL (__stdcall *GCCC_LaunchGCWithDimensions)(int, int, int, int);
+typedef int (__stdcall *GCCC_GoogleChromeDaysSinceLastRun)();
 }  // extern "C"
 
 #endif  // CHROME_INSTALLER_GCAPI_GCAPI_H_