Make ModelLoader to release URLFeatcher once fetching is done.

chrome/browser/safe_browsing/client_side_model_loader.cc

Index: chrome/browser/safe_browsing/client_side_model_loader.cc
diff --git a/chrome/browser/safe_browsing/client_side_model_loader.cc b/chrome/browser/safe_browsing/client_side_model_loader.cc
index 5519b4108b0cdf907a65ff6815bc52de9dc30a40..9be0e957eed2b1af11825631ed3459471c292646 100644
--- a/chrome/browser/safe_browsing/client_side_model_loader.cc
+++ b/chrome/browser/safe_browsing/client_side_model_loader.cc
@@ -189,14 +189,19 @@ void ModelLoader::EndFetch(ClientModelStatus status, base::TimeDelta max_age) {
     delay_ms = max_age.InMilliseconds();
   }
 
+  // Reset |fetcher_| as long as it will be re-created on next fetch.

[mattm, 2017/01/30 20:23:13]

Wording is a little confusing, I'd remove the "as long", eg: "Reset |fetcher_|
as it will be re-created on next fetch."

[maksims (do not use this acc), 2017/01/31 05:50:28]

Done.

+  fetcher_.reset();
+
   // Schedule the next model reload.
   ScheduleFetch(delay_ms);
 }
 
 void ModelLoader::ScheduleFetch(int64_t delay_ms) {
   if (base::CommandLine::ForCurrentProcess()->HasSwitch(
-          safe_browsing::switches::kSbDisableAutoUpdate))
+          safe_browsing::switches::kSbDisableAutoUpdate)) {
+    CancelFetcher();

[mattm, 2017/01/30 20:23:13]

This seems unnecessary, can you explain when this would matter?

[maksims (do not use this acc), 2017/01/31 05:50:28]

I thought it would be necessary if fetch had been scheduled before switch became
disabled. But it requires restart of the browser.

     return;
+  }
   base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
       FROM_HERE,
       base::Bind(&ModelLoader::StartFetch, weak_factory_.GetWeakPtr()),
@@ -207,7 +212,8 @@ void ModelLoader::CancelFetcher() {
   // Invalidate any scheduled request.
   weak_factory_.InvalidateWeakPtrs();
   // Cancel any request in progress.
-  fetcher_.reset();
+  if (fetcher_)

[mattm, 2017/01/30 20:23:13]

unnecessary

[maksims (do not use this acc), 2017/01/31 05:50:28]

Done.

+    fetcher_.reset();
 }
 
 }  // namespace safe_browsing