Add --disable-drive-prefetch flag for ChromeOS.

chrome/common/chrome_switches.cc

Index: chrome/common/chrome_switches.cc
diff --git a/chrome/common/chrome_switches.cc b/chrome/common/chrome_switches.cc
index 3e409d87360e20499764b64e469c8d672f6c1c5c..ed9c9d7a20c17248c9525761de96dce644201980 100644
--- a/chrome/common/chrome_switches.cc
+++ b/chrome/common/chrome_switches.cc
@@ -1379,6 +1379,9 @@ const char kEnableCarrierSwitching[]        = "enable-carrier-switching";
 // Disables wallpaper boot animation (except of OOBE case).
 const char kDisableBootAnimation[]          = "disable-boot-animation";
 
+// Disables file prefetching in Google Drive Client for Chrome OS.
+const char kDisableDrivePrefetch[]          = "disable-drive-prefetch";
+
 // Disables reset the device to its factory state in design.
 const char kDisableFactoryReset[]           = "disable-factory-reset";