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 f99f3c20f56d889b94fee0598e5b2d58e9cf48f5..32af3f71f46021f52cbeebb0f7866e3207b7be12 100644
--- a/chrome/browser/bitmap_fetcher/bitmap_fetcher.cc
+++ b/chrome/browser/bitmap_fetcher/bitmap_fetcher.cc
@@ -19,10 +19,10 @@ BitmapFetcher::BitmapFetcher(const GURL& url, BitmapFetcherDelegate* delegate)
 BitmapFetcher::~BitmapFetcher() {
 }
 
-void BitmapFetcher::Start(net::URLRequestContextGetter* request_context,
-                          const std::string& referrer,
-                          net::URLRequest::ReferrerPolicy referrer_policy,
-                          int load_flags) {
+void BitmapFetcher::Init(net::URLRequestContextGetter* request_context,
+                         const std::string& referrer,
+                         net::URLRequest::ReferrerPolicy referrer_policy,
+                         int load_flags) {
   if (url_fetcher_ != NULL)

[sky, 2015/06/08 15:05:29]

In general we DCHECK people calling Init multiple times.

     return;
 
@@ -31,6 +31,9 @@ void BitmapFetcher::Start(net::URLRequestContextGetter* request_context,
   url_fetcher_->SetReferrer(referrer);
   url_fetcher_->SetReferrerPolicy(referrer_policy);
   url_fetcher_->SetLoadFlags(load_flags);
+}
+
+void BitmapFetcher::Start() {
   url_fetcher_->Start();

[sky, 2015/06/08 15:05:29]

The old code early outed if url_fecher_ was already set. Why is that not
necessary anymore?

 }