Add possibility to define data callback to BitmapFetcher

chrome/browser/bitmap_fetcher/bitmap_fetcher.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/bitmap_fetcher/bitmap_fetcher.h"
 
 #include "content/public/browser/browser_thread.h"
 #include "net/url_request/url_fetcher.h"
 #include "net/url_request/url_request_context_getter.h"
 #include "net/url_request/url_request_status.h"
@@ skipping 10 matching lines @@
 BitmapFetcher::~BitmapFetcher() {
 }
 
 void BitmapFetcher::Start(net::URLRequestContextGetter* request_context,
                           const std::string& referrer,
                           net::URLRequest::ReferrerPolicy referrer_policy,
                           int load_flags) {
   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();
+}
+
 // Methods inherited from URLFetcherDelegate.
 
 void BitmapFetcher::OnURLFetchComplete(const net::URLFetcher* source) {
   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
 
   if (source->GetStatus().status() != net::URLRequestStatus::SUCCESS) {
     ReportFailure();
     return;
   }
 
@@ skipping 19 matching lines @@
 }
 
 void BitmapFetcher::OnDecodeImageFailed() {
   ReportFailure();
 }
 
 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