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

chrome/installer/gcapi/gcapi.h

-// 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.
 
 #ifndef CHROME_INSTALLER_GCAPI_GCAPI_H_
 #define CHROME_INSTALLER_GCAPI_GCAPI_H_
 #pragma once
 
 #include <windows.h>
 
 extern "C" {
 // Error conditions for GoogleChromeCompatibilityCheck().
 #define GCCC_ERROR_USERLEVELALREADYPRESENT       0x01
 #define GCCC_ERROR_SYSTEMLEVELALREADYPRESENT     0x02
 #define GCCC_ERROR_ACCESSDENIED                  0x04
 #define GCCC_ERROR_OSNOTSUPPORTED                0x08
 #define GCCC_ERROR_ALREADYOFFERED                0x10
 #define GCCC_ERROR_INTEGRITYLEVEL                0x20
 
 #define DLLEXPORT __declspec(dllexport)
 
 // This function returns TRUE if Google Chrome should be offered.
 // If the return is FALSE, the reasons DWORD explains why.  If you don't care
 // for the reason, you can pass NULL for reasons.
 // set_flag indicates whether a flag should be set indicating that Chrome was
 // offered within the last six months; if passed FALSE, this method will not
 // 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
 // you called CoInitialize, call CoUninitialize before calling this function).
 DLLEXPORT BOOL __stdcall LaunchGoogleChrome();
 
 // This function launches Google Chrome after a successful install at the
 // given x,y coordinates with size height,length. Make
 // sure COM library is NOT initalized before you call this function (so if
 // you called CoInitialize, call CoUninitialize before calling this function).
 // This call is synchronous, meaning it waits for Chrome to launch and appear
 // to resize it before returning.
 DLLEXPORT BOOL __stdcall LaunchGoogleChromeWithDimensions(int x,
                                                           int y,
                                                           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_