Make application shortcuts point to app_host.exe, install App Host during app installation.

chrome/installer/launcher_support/chrome_launcher_support.h

Index: chrome/installer/launcher_support/chrome_launcher_support.h
diff --git a/chrome/installer/launcher_support/chrome_launcher_support.h b/chrome/installer/launcher_support/chrome_launcher_support.h
index 1051a244586e0e337bf2d23253e99904492080f2..bf608250c4af34d6afd2763a5f933188ebe380d6 100644
--- a/chrome/installer/launcher_support/chrome_launcher_support.h
+++ b/chrome/installer/launcher_support/chrome_launcher_support.h
@@ -24,6 +24,10 @@ FilePath GetSetupExeForInstallationLevel(InstallationLevel level);
 // exists.
 FilePath GetChromePathForInstallationLevel(InstallationLevel level);
 
+// Returns the path to an installed app_host.exe at the specified level, if
+// it can be found via Omaha client state.
+FilePath GetAppHostPathForInstallationLevel(InstallationLevel level);
+
 // Returns the path to an installed chrome.exe, or an empty path. Prefers a
 // system-level installation to a user-level installation. Uses Omaha client
 // state to identify a Chrome installation location.
@@ -32,6 +36,18 @@ FilePath GetChromePathForInstallationLevel(InstallationLevel level);
 // The file path returned (if any) is guaranteed to exist.
 FilePath GetAnyChromePath();
 
+// Returns the path to an installed app_host.exe, or an empty path. Prefers a
+// system-level installation to a user-level installation. Uses Omaha client
+// state to identify a App Host installation location.
+// In non-official builds, to ease development, this will first look for a
+// app_host.exe in the same directory as the current executable.
+// The file path returned (if any) is guaranteed to exist.
+FilePath GetAnyAppHostPath();
+
+// Returns true if App Host is installed (system-level or user-level),
+// or in the same directory as the current executable.
+bool IsAppHostPresent();
+
 }  // namespace chrome_launcher_support
 
 #endif  // CHROME_INSTALLER_LAUNCHER_SUPPORT_CHROME_LAUNCHER_SUPPORT_H_