Make OnDataTimedout and OnDidPerformInstallableCheck mutually exclusive.

chrome/browser/android/webapps/add_to_homescreen_data_fetcher.cc

Index: chrome/browser/android/webapps/add_to_homescreen_data_fetcher.cc
diff --git a/chrome/browser/android/webapps/add_to_homescreen_data_fetcher.cc b/chrome/browser/android/webapps/add_to_homescreen_data_fetcher.cc
index 2dea7aa3a00b0457d742b1b3fc685e6c50b030e1..8091cf667fc057e9ad63bfd30e8240a50976b143 100644
--- a/chrome/browser/android/webapps/add_to_homescreen_data_fetcher.cc
+++ b/chrome/browser/android/webapps/add_to_homescreen_data_fetcher.cc
@@ -212,7 +212,10 @@ void AddToHomescreenDataFetcher::OnDidPerformInstallableCheck(
   if (!web_contents() || !weak_observer_)
     return;
 
-  is_installable_check_complete_ = true;
+  if (is_installable_check_complete_)
+    return;

[pkotwicz, 2017/02/27 23:30:38]

Nit:
You can remove the else

In Chrome we prefer
if (a) {
  // do work
  return;
}
// do work


Instead of
if (a) {
  // do work
  return;
} else {
  // do work
}

[F, 2017/02/28 23:09:42]

Done.

+  else
+    is_installable_check_complete_ = true;
 
   bool webapk_compatible = false;
   if (check_webapk_compatibility_) {