Add possibility to define data callback to BitmapFetcher

chrome/browser/bitmap_fetcher/bitmap_fetcher.cc

Index: chrome/browser/bitmap_fetcher/bitmap_fetcher.cc
diff --git a/chrome/browser/bitmap_fetcher/bitmap_fetcher.cc b/chrome/browser/bitmap_fetcher/bitmap_fetcher.cc
index e413fa1a8e35de6643623c4434156ea5de9f9941..1f075916de2ab8f9ff295d9608a7ff48b1847b93 100644
--- a/chrome/browser/bitmap_fetcher/bitmap_fetcher.cc
+++ b/chrome/browser/bitmap_fetcher/bitmap_fetcher.cc
@@ -28,11 +28,28 @@ void BitmapFetcher::Start(net::URLRequestContextGetter* request_context,
   if (url_fetcher_ != NULL)
     return;
 
-  url_fetcher_.reset(net::URLFetcher::Create(url_, net::URLFetcher::GET, this));
-  url_fetcher_->SetRequestContext(request_context);
-  url_fetcher_->SetReferrer(referrer);
-  url_fetcher_->SetReferrerPolicy(referrer_policy);
-  url_fetcher_->SetLoadFlags(load_flags);
+  url_fetcher_ = CreateURLFetcher(request_context,
+                                  referrer,
+                                  referrer_policy,
+                                  load_flags);
+  url_fetcher_->Start();
+}
+
+void BitmapFetcher::Start(

[Peter Kasting, 2015/04/22 23:16:20]

I'm not a fan of having these two methods which have almost-identical args and
code.  And what happens in the future when someone wants to set some other piece
of info on the underlying URL fetcher?

Instead, I would split things into BitmapFetcher::CreateURLFetcher(), an inlined
BitmapFetcher::url_fetcher() non-const accessor that callers can use to do
things like call SetURLRequestUserData(), and a BitmapFetcher::Start() function
that just calls through to the underlying Start().  (This last is optional;
callers could just as easily call url_fetcher()->Start().)

+    net::URLRequestContextGetter* request_context,
+    const std::string& referrer,
+    net::URLRequest::ReferrerPolicy referrer_policy,
+    int load_flags,
+    const void* user_data_key,
+    const net::URLFetcher::CreateDataCallback& create_data_callback) {
+  if (url_fetcher_ != NULL)
+    return;
+
+  url_fetcher_ = CreateURLFetcher(request_context,
+                                  referrer,
+                                  referrer_policy,
+                                  load_flags);
+  url_fetcher_->SetURLRequestUserData(user_data_key, create_data_callback);
   url_fetcher_->Start();
 }
 
@@ -75,4 +92,18 @@ void BitmapFetcher::ReportFailure() {
   delegate_->OnFetchComplete(url_, NULL);
 }
 
+scoped_ptr<net::URLFetcher> BitmapFetcher::CreateURLFetcher(
+    net::URLRequestContextGetter* request_context,
+    const std::string& referrer,
+    net::URLRequest::ReferrerPolicy referrer_policy,
+    int load_flags) {
+  scoped_ptr<net::URLFetcher> fetcher(
+      net::URLFetcher::Create(url_, net::URLFetcher::GET, this));
+  fetcher->SetRequestContext(request_context);
+  fetcher->SetReferrer(referrer);
+  fetcher->SetReferrerPolicy(referrer_policy);
+  fetcher->SetLoadFlags(load_flags);
+  return fetcher;
+}
+
 }  // namespace chrome