Adds a basic offline check to InstallableManager.

chrome/browser/installable/installable_logging.cc

Index: chrome/browser/installable/installable_logging.cc
diff --git a/chrome/browser/installable/installable_logging.cc b/chrome/browser/installable/installable_logging.cc
index 6f0cdc4234663866ee29a6e93d5e3edd60658f70..6a9abfd63d47e654c12714480dcefc3e5a190337 100644
--- a/chrome/browser/installable/installable_logging.cc
+++ b/chrome/browser/installable/installable_logging.cc
@@ -64,7 +64,8 @@ static const char kUrlNotSupportedForWebApkMessage[] =
     "a URL in the web manifest contains a username, password, or port";
 static const char kInIncognitoMessage[] =
     "the page is loaded in an incognito window";
-
+static const char kNoServiceWorkerFetchHandlerMessage[] =
+    "a fetch handler is not present in the service worker";

[dominickn, 2017/03/16 06:21:56]

Nit: let's just make this "the page does not work offline". That way this
message will stay true over time as we ratchet up the checks.

[piotrs, 2017/03/17 02:21:37]

Like it, thanks. Also it doesn't expose our internal (and arguably not very
comprehensive) check.

 }  // namespace
 
 void LogErrorToConsole(content::WebContents* web_contents,
@@ -151,6 +152,9 @@ void LogErrorToConsole(content::WebContents* web_contents,
     case IN_INCOGNITO:
       pattern = kInIncognitoMessage;
       break;
+    case NO_SERVICE_WORKER_FETCH_HANDLER:
+      pattern = kNoServiceWorkerFetchHandlerMessage;
+      break;
   }
 
   if (!pattern)