Cleanup image_fetcher::ImageFetcher

Follow-up CL to address comments on https://codereview.chromium.org/787903003
after the CL landed:
- cleanup #includes in image_fetcher.{h,mm}
- use const ref to scoped_refptr to avoid inc/dec ref churn
- prefer base::ThreadTaskRunnerHandle::Get() to MessageLoopProxy::current()
- remove std::string concatenation

BUG=None

Review URL: https://codereview.chromium.org/805713004

Cr-Commit-Position: refs/heads/master@{#308347}

4 files changed, 68 insertions, 63 deletions

diff --git a/ios/chrome/browser/net/image_fetcher.h b/ios/chrome/browser/net/image_fetcher.h
index db6c055..34b0aca 100644
--- a/ios/chrome/browser/net/image_fetcher.h
+++ b/ios/chrome/browser/net/image_fetcher.h
@@ -7,35 +7,42 @@
 
 #include <map>
 
-#include "base/compiler_specific.h"
-#include "base/mac/bind_objc_block.h"
-#include "base/mac/scoped_nsobject.h"
+#include "base/mac/scoped_block.h"
+#include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "net/url_request/url_fetcher_delegate.h"
 #include "net/url_request/url_request.h"
-#include "net/url_request/url_request_context_getter.h"
-#include "url/gurl.h"
 
+class GURL;
 @class NSData;
 
+namespace base {
+class SequencedWorkerPool;
+}
+
+namespace net {
+class URLRequestContextGetter;
+}
+
 namespace image_fetcher {
 
 // Callback that informs of the download of an image encoded in |data|,
 // downloaded from |url|, and with the http status |http_response_code|. If the
 // url is a data URL, |http_response_code| is always 200.
-typedef void (^Callback)(const GURL& url, int http_response_code, NSData* data);
+using ImageFetchedCallback =
+    void (^)(const GURL& url, int http_response_code, NSData* data);
 
 // Utility class that will retrieve an image from an URL. The image is returned
 // as NSData which can be used with +[UIImage imageWithData:]. This class
 // usually returns the raw bytes retrieved from the network without any
-// processing with the exception of WebP encoded images. Those are decoded and
+// processing, with the exception of WebP encoded images. Those are decoded and
 // then reencoded in a format suitable for UIImage.
 // An instance of this class can download a number of images at the same time.
 class ImageFetcher : public net::URLFetcherDelegate {
  public:
   // The WorkerPool is used to eventually decode the image.
   explicit ImageFetcher(
-      const scoped_refptr<base::SequencedWorkerPool> decoding_pool);
+      const scoped_refptr<base::SequencedWorkerPool>& decoding_pool);
   ~ImageFetcher() override;
 
   // Start downloading the image at the given |url|. The |callback| will be
@@ -45,25 +52,25 @@ class ImageFetcher : public net::URLFetcherDelegate {
   // This method assumes the request context getter has been set.
   // (virtual for testing)
   virtual void StartDownload(const GURL& url,
-                             Callback callback,
+                             ImageFetchedCallback callback,
                              const std::string& referrer,
                              net::URLRequest::ReferrerPolicy referrer_policy);
 
   // Helper method to call StartDownload without a referrer.
   // (virtual for testing)
-  virtual void StartDownload(const GURL& url, Callback callback);
+  virtual void StartDownload(const GURL& url, ImageFetchedCallback callback);
 
   // A valid request context getter is required before starting the download.
   // (virtual for testing)
-  virtual void SetRequestContextGetter(
-      net::URLRequestContextGetter* request_context_getter);
+  virtual void SetRequestContextGetter(const scoped_refptr<
+      net::URLRequestContextGetter>& request_context_getter);
 
-  // content::URLFetcherDelegate methods.
+  // net::URLFetcherDelegate:
   void OnURLFetchComplete(const net::URLFetcher* source) override;
 
  private:
   // Runs the callback with the given arguments.
-  void RunCallback(const base::mac::ScopedBlock<Callback>& callback,
+  void RunCallback(const base::mac::ScopedBlock<ImageFetchedCallback>& callback,
                    const GURL& url,
                    const int http_response_code,
                    NSData* data);
@@ -72,7 +79,7 @@ class ImageFetcher : public net::URLFetcherDelegate {
   // fetch; the value is the callback to use when the download request
   // completes. When a download request completes, the URLFetcher must be
   // deleted and the callback called and released.
-  std::map<const net::URLFetcher*, Callback> downloads_in_progress_;
+  std::map<const net::URLFetcher*, ImageFetchedCallback> downloads_in_progress_;
   scoped_refptr<net::URLRequestContextGetter> request_context_getter_;
 
   // The WeakPtrFactory is used to cancel callbacks if ImageFetcher is destroyed
diff --git a/ios/chrome/browser/net/image_fetcher.mm b/ios/chrome/browser/net/image_fetcher.mm
index e40dcdf..15170e9 100644
--- a/ios/chrome/browser/net/image_fetcher.mm
+++ b/ios/chrome/browser/net/image_fetcher.mm
@@ -7,18 +7,15 @@
 #import <Foundation/Foundation.h>
 
 #include "base/bind.h"
-#include "base/compiler_specific.h"
 #include "base/location.h"
-#include "base/logging.h"
-#include "base/mac/scoped_block.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/task_runner_util.h"
+#include "base/mac/scoped_nsobject.h"
 #include "base/threading/sequenced_worker_pool.h"
+#include "ios/web/public/web_thread.h"
 #include "ios/web/public/webp_decoder.h"
 #include "net/base/load_flags.h"
 #include "net/http/http_response_headers.h"
 #include "net/url_request/url_fetcher.h"
-#include "url/gurl.h"
+#include "net/url_request/url_request_context_getter.h"
 
 namespace {
 
@@ -45,6 +42,9 @@ class WebpDecoderDelegate : public web::WebpDecoder::Delegate {
   base::scoped_nsobject<NSMutableData> decoded_image_;
 };
 
+// Content-type header for WebP images.
+static const char kWEBPMimeType[] = "image/webp";
+
 // Returns a NSData object containing the decoded image.
 // Returns nil in case of failure.
 base::scoped_nsobject<NSData> DecodeWebpImage(
@@ -61,7 +61,7 @@ base::scoped_nsobject<NSData> DecodeWebpImage(
 namespace image_fetcher {
 
 ImageFetcher::ImageFetcher(
-    const scoped_refptr<base::SequencedWorkerPool> decoding_pool)
+    const scoped_refptr<base::SequencedWorkerPool>& decoding_pool)
     : request_context_getter_(nullptr),
       weak_factory_(this),
       decoding_pool_(decoding_pool) {
@@ -71,17 +71,15 @@ ImageFetcher::ImageFetcher(
 ImageFetcher::~ImageFetcher() {
   // Delete all the entries in the |downloads_in_progress_| map.  This will in
   // turn cancel all of the requests.
-  for (std::map<const net::URLFetcher*, Callback>::iterator it =
-           downloads_in_progress_.begin();
-       it != downloads_in_progress_.end(); ++it) {
-    [it->second release];
-    delete it->first;
+  for (const auto& pair : downloads_in_progress_) {
+    [pair.second release];
+    delete pair.first;
   }
 }
 
 void ImageFetcher::StartDownload(
     const GURL& url,
-    Callback callback,
+    ImageFetchedCallback callback,
     const std::string& referrer,
     net::URLRequest::ReferrerPolicy referrer_policy) {
   DCHECK(request_context_getter_.get());
@@ -90,16 +88,18 @@ void ImageFetcher::StartDownload(
                                                      this);
   downloads_in_progress_[fetcher] = [callback copy];
   fetcher->SetLoadFlags(
-      net::LOAD_DO_NOT_SEND_COOKIES | net::LOAD_DO_NOT_SAVE_COOKIES);
+      net::LOAD_DO_NOT_SEND_COOKIES | net::LOAD_DO_NOT_SAVE_COOKIES |
+      net::LOAD_DO_NOT_SEND_AUTH_DATA | net::LOAD_DO_NOT_PROMPT_FOR_LOGIN);
   fetcher->SetRequestContext(request_context_getter_.get());
   fetcher->SetReferrer(referrer);
   fetcher->SetReferrerPolicy(referrer_policy);
   fetcher->Start();
 }
 
-void ImageFetcher::StartDownload(const GURL& url, Callback callback) {
+void ImageFetcher::StartDownload(
+    const GURL& url, ImageFetchedCallback callback) {
   ImageFetcher::StartDownload(
-      url, callback, "", net::URLRequest::NEVER_CLEAR_REFERRER);
+      url, callback, std::string(), net::URLRequest::NEVER_CLEAR_REFERRER);
 }
 
 // Delegate callback that is called when URLFetcher completes.  If the image
@@ -111,19 +111,20 @@ void ImageFetcher::OnURLFetchComplete(const net::URLFetcher* fetcher) {
     return;
   }
 
-  // Ensures that |fetcher| will be deleted even if we return early.
+  // Ensures that |fetcher| will be deleted in the event of early return.
   scoped_ptr<const net::URLFetcher> fetcher_deleter(fetcher);
 
-  // Retrieves the callback and ensures that it will be deleted even if we
-  // return early.
-  base::mac::ScopedBlock<Callback> callback(downloads_in_progress_[fetcher]);
+  // Retrieves the callback and ensures that it will be deleted in the event
+  // of early return.
+  base::mac::ScopedBlock<ImageFetchedCallback> callback(
+      downloads_in_progress_[fetcher]);
 
   // Remove |fetcher| from the map.
   downloads_in_progress_.erase(fetcher);
 
   // Make sure the request was successful. For "data" requests, the response
   // code has no meaning, because there is no actual server (data is encoded
-  // directly in the URL). In that case, we set the response code to 200.
+  // directly in the URL). In that case, set the response code to 200 (OK).
   const GURL& original_url = fetcher->GetOriginalURL();
   const int http_response_code = original_url.SchemeIs("data") ?
       200 : fetcher->GetResponseCode();
@@ -146,7 +147,7 @@ void ImageFetcher::OnURLFetchComplete(const net::URLFetcher* fetcher) {
   if (fetcher->GetResponseHeaders()) {
     std::string mime_type;
     fetcher->GetResponseHeaders()->GetMimeType(&mime_type);
-    if (mime_type == "image/webp") {
+    if (mime_type == kWEBPMimeType) {
       base::PostTaskAndReplyWithResult(decoding_pool_.get(),
                                        FROM_HERE,
                                        base::Bind(&DecodeWebpImage, data),
@@ -161,15 +162,16 @@ void ImageFetcher::OnURLFetchComplete(const net::URLFetcher* fetcher) {
   (callback.get())(original_url, http_response_code, data);
 }
 
-void ImageFetcher::RunCallback(const base::mac::ScopedBlock<Callback>& callback,
-                               const GURL& url,
-                               int http_response_code,
-                               NSData* data) {
+void ImageFetcher::RunCallback(
+    const base::mac::ScopedBlock<ImageFetchedCallback>& callback,
+    const GURL& url,
+    int http_response_code,
+    NSData* data) {
   (callback.get())(url, http_response_code, data);
 }
 
 void ImageFetcher::SetRequestContextGetter(
-    net::URLRequestContextGetter* request_context_getter) {
+    const scoped_refptr<net::URLRequestContextGetter>& request_context_getter) {
   request_context_getter_ = request_context_getter;
 }
 
diff --git a/ios/chrome/browser/net/image_fetcher_unittest.mm b/ios/chrome/browser/net/image_fetcher_unittest.mm
index 6f23525..c62446c 100644
--- a/ios/chrome/browser/net/image_fetcher_unittest.mm
+++ b/ios/chrome/browser/net/image_fetcher_unittest.mm
@@ -6,14 +6,12 @@
 
 #import <UIKit/UIKit.h>
 
-#include "base/mac/bind_objc_block.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/message_loop/message_loop_proxy.h"
+#include "base/mac/scoped_block.h"
+#include "base/memory/ref_counted.h"
 #include "base/run_loop.h"
-#include "base/threading/sequenced_worker_pool.h"
+#include "base/thread_task_runner_handle.h"
 #include "net/http/http_response_headers.h"
 #include "net/url_request/test_url_fetcher_factory.h"
-#include "net/url_request/url_fetcher_delegate.h"
 #include "net/url_request/url_request_test_util.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/platform_test.h"
@@ -59,10 +57,16 @@ static unsigned char kWEBPImage[] = {
     48,1,0,157,1,42,1,0,1,0,3,0,52,37,164,0,3,112,0,254,251,253,80,0
 };
 
-static char kTestUrl[] = "http://www.img.com";
+static const char kTestUrl[] = "http://www.img.com";
+
+static const char kWEBPHeaderResponse[] =
+    "HTTP/1.1 200 OK\0Content-type: image/webp\0\0";
 
 }  // namespace
 
+// TODO(ios): remove the static_cast<UIImage*>(nil) once all the bots have
+// Xcode 6.0 or later installed, http://crbug.com/440857
+
 class ImageFetcherTest : public PlatformTest {
  protected:
   ImageFetcherTest()
@@ -77,7 +81,7 @@ class ImageFetcherTest : public PlatformTest {
         } copy]);
     image_fetcher_->SetRequestContextGetter(
         new net::TestURLRequestContextGetter(
-            base::MessageLoopProxy::current()));
+            base::ThreadTaskRunnerHandle::Get()));
   }
 
   ~ImageFetcherTest() override { pool_->Shutdown(); }
@@ -93,7 +97,7 @@ class ImageFetcherTest : public PlatformTest {
   }
 
   base::MessageLoop loop_;
-  base::mac::ScopedBlock<image_fetcher::Callback> callback_;
+  base::mac::ScopedBlock<image_fetcher::ImageFetchedCallback> callback_;
   net::TestURLFetcherFactory factory_;
   scoped_refptr<base::SequencedWorkerPool> pool_;
   scoped_ptr<image_fetcher::ImageFetcher> image_fetcher_;
@@ -132,11 +136,8 @@ TEST_F(ImageFetcherTest, TestGoodWebP) {
   fetcher->set_response_code(200);
   fetcher->SetResponseString(
       std::string((char*)kWEBPImage, sizeof(kWEBPImage)));
-  std::string kZero = std::string("\0", 1);
-  std::string header_string = std::string("HTTP/1.1 200 OK") + kZero +
-      "Content-type: image/webp" + kZero + kZero;
   scoped_refptr<net::HttpResponseHeaders> headers(new net::HttpResponseHeaders(
-      header_string));
+      std::string(kWEBPHeaderResponse, arraysize(kWEBPHeaderResponse))));
   fetcher->set_response_headers(headers);
   fetcher->delegate()->OnURLFetchComplete(fetcher);
   pool_->FlushForTesting();
@@ -149,11 +150,8 @@ TEST_F(ImageFetcherTest, TestBadWebP) {
   net::TestURLFetcher* fetcher = SetupFetcher();
   fetcher->set_response_code(200);
   fetcher->SetResponseString("This is not a valid WebP image");
-  std::string kZero = std::string("\0", 1);
-  std::string header_string = std::string("HTTP/1.1 200 OK") + kZero +
-      "Content-type: image/webp" + kZero + kZero;
   scoped_refptr<net::HttpResponseHeaders> headers(new net::HttpResponseHeaders(
-      header_string));
+      std::string(kWEBPHeaderResponse, arraysize(kWEBPHeaderResponse))));
   fetcher->set_response_headers(headers);
   fetcher->delegate()->OnURLFetchComplete(fetcher);
   pool_->FlushForTesting();
@@ -167,11 +165,8 @@ TEST_F(ImageFetcherTest, DeleteDuringWebPDecoding) {
   fetcher->set_response_code(200);
   fetcher->SetResponseString(
       std::string((char*)kWEBPImage, sizeof(kWEBPImage)));
-  std::string kZero = std::string("\0", 1);
-  std::string header_string = std::string("HTTP/1.1 200 OK") + kZero +
-      "Content-type: image/webp" + kZero + kZero;
   scoped_refptr<net::HttpResponseHeaders> headers(new net::HttpResponseHeaders(
-      header_string));
+      std::string(kWEBPHeaderResponse, arraysize(kWEBPHeaderResponse))));
   fetcher->set_response_headers(headers);
   fetcher->delegate()->OnURLFetchComplete(fetcher);
   // Delete the image fetcher, and check that the callback is not called.
diff --git a/ios/chrome/browser/suggestions/image_fetcher_impl.mm b/ios/chrome/browser/suggestions/image_fetcher_impl.mm
index 78f20e6..01cde48 100644
--- a/ios/chrome/browser/suggestions/image_fetcher_impl.mm
+++ b/ios/chrome/browser/suggestions/image_fetcher_impl.mm
@@ -8,6 +8,7 @@
 
 #include "base/threading/sequenced_worker_pool.h"
 #include "ios/chrome/browser/net/image_fetcher.h"
+#include "net/url_request/url_request_context_getter.h"
 #include "skia/ext/skia_utils_ios.h"
 
 namespace suggestions {
@@ -40,7 +41,7 @@ void ImageFetcherImpl::StartOrQueueNetworkRequest(
   }
   // Copy url reference so it's retained.
   const GURL page_url(url);
-  image_fetcher::Callback fetcher_callback =
+  image_fetcher::ImageFetchedCallback fetcher_callback =
       ^(const GURL& original_url, int response_code, NSData* data) {
       if (data) {
         // Most likely always returns 1x images.