Reland DownloadTaskImpl implementation for //ios/web Download API.

This CL implements DownloadTask public interface.

DownloadControllerImpl CL: crrev.com/c/758525
Design doc: http://go/ios-web-download-api

Bug: 780646
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: Iffea44bfb64cc945f7d899dd7181556a730394f1
Reviewed-on: https://chromium-review.googlesource.com/775889Reviewed-by: Sylvain Defresne <sdefresne@chromium.org>
Commit-Queue: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#517424}

ios/web/BUILD.gn

@@ -40,6 +40,7 @@ source_set("web") {
     ":navigation_resources",
     ":resources",
     "//base",
+    "//ios/web/download",
     "//ios/web/interstitials",
     "//ios/web/navigation",
     "//ios/web/net",
@@ -166,6 +167,7 @@ test("ios_web_unittests") {
     ":ios_web_web_state_unittests",
     ":ios_web_webui_unittests",
     "//ios/testing:http_server_bundle_data",
+    "//ios/web/download:download_unittests",
   ]
 
   assert_no_deps = ios_assert_no_deps

ios/web/download/BUILD.gn

+# Copyright 2017 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.
+
+import("//ios/build/config.gni")
+
+source_set("download") {
+  deps = [
+    "//base",
+    "//ios/web/net/cookies",
+    "//ios/web/public",
+    "//ios/web/public/download",
+    "//ios/web/web_state:error_translation_util",
+  ]
+
+  sources = [
+    "download_task_impl.h",
+    "download_task_impl.mm",
+  ]
+
+  libs = [ "UIKit.framework" ]
+
+  configs += [ "//build/config/compiler:enable_arc" ]
+}
+
+source_set("download_unittests") {
+  configs += [ "//build/config/compiler:enable_arc" ]
+  testonly = true
+  deps = [
+    "//base",
+    "//ios/testing:ios_test_support",
+    "//ios/testing:ocmock_support",
+    "//ios/web/download",
+    "//ios/web/net/cookies",
+    "//ios/web/public/download",
+    "//ios/web/public/test",
+    "//ios/web/public/test/fakes",
+    "//ios/web/test/fakes",
+    "//net",
+    "//testing/gmock",
+    "//testing/gtest",
+  ]
+
+  sources = [
+    "download_task_impl_unittest.mm",
+  ]
+}

ios/web/download/OWNERS

+eugenebut@chromium.org
+gchatz@chromium.org
+
+# TEAM: ios-directory-owners@chromium.org
+# OS: iOS

ios/web/download/download_task_impl.h

+// Copyright 2017 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.
+
+#ifndef IOS_WEB_DOWNLOAD_DOWNLOAD_TASK_IMPL_H_
+#define IOS_WEB_DOWNLOAD_DOWNLOAD_TASK_IMPL_H_
+
+#include <string>
+
+#include "base/memory/weak_ptr.h"
+#include "base/observer_list.h"
+#import "ios/web/public/download/download_task.h"
+#include "url/gurl.h"
+
+@class NSURLSession;
+
+namespace net {
+class URLFetcherResponseWriter;
+}
+
+namespace web {
+
+class DownloadTaskObserver;
+class WebState;
+
+// Implements DownloadTask interface. Uses background NSURLSession as
+// implementation.
+class DownloadTaskImpl : public DownloadTask {
+ public:
+  class Delegate {
+   public:
+    // Called when download task is about to be destroyed. Delegate should
+    // remove all references to the given DownloadTask and stop using it.
+    virtual void OnTaskDestroyed(DownloadTaskImpl* task) = 0;
+
+    // Creates background NSURLSession with given |identifier|, |delegate| and
+    // |delegate_queue|.
+    virtual NSURLSession* CreateSession(NSString* identifier,
+                                        id<NSURLSessionDataDelegate> delegate,
+                                        NSOperationQueue* delegate_queue) = 0;
+    virtual ~Delegate() = default;
+  };
+
+  // Constructs a new DownloadTaskImpl objects. |web_state|, |identifier| and
+  // |delegate| must be valid.
+  DownloadTaskImpl(const WebState* web_state,
+                   const GURL& original_url,
+                   const std::string& content_disposition,
+                   int64_t total_bytes,
+                   const std::string& mime_type,
+                   NSString* identifier,
+                   Delegate* delegate);
+
+  // Stops the download operation and clears the delegate.
+  void ShutDown();
+
+  // DownloadTask overrides:
+  void Start(std::unique_ptr<net::URLFetcherResponseWriter> writer) override;
+  net::URLFetcherResponseWriter* GetResponseWriter() const override;
+  NSString* GetIndentifier() const override;
+  const GURL& GetOriginalUrl() const override;
+  bool IsDone() const override;
+  int GetErrorCode() const override;
+  int64_t GetTotalBytes() const override;
+  int GetPercentComplete() const override;
+  std::string GetContentDisposition() const override;
+  std::string GetMimeType() const override;
+  base::string16 GetSuggestedFilename() const override;
+  void AddObserver(DownloadTaskObserver* observer) override;
+  void RemoveObserver(DownloadTaskObserver* observer) override;
+  ~DownloadTaskImpl() override;
+
+ private:
+  // Creates background NSURLSession with given |identifier|.
+  NSURLSession* CreateSession(NSString* identifier);
+
+  // Asynchronously returns cookies for WebState associated with this task (on
+  // iOS 10 and earlier, the array is always empty as it is not possible to
+  // access the cookies). Must be called on UI thread. The callback will be
+  // invoked on the UI thread.
+  void GetCookies(base::Callback<void(NSArray<NSHTTPCookie*>*)> callback);
+
+  // Asynchronously returns cookies for WebState associated with this task. Must
+  // be called on UI thread. The callback will be invoked on the UI thread.
+  void GetWKCookies(base::Callback<void(NSArray<NSHTTPCookie*>*)> callback)
+      API_AVAILABLE(ios(11.0));
+
+  // Starts the download with given cookies.
+  void StartWithCookies(NSArray<NSHTTPCookie*>* cookies);
+
+  // Called when download task was updated.
+  void OnDownloadUpdated();
+
+  // Called when download was completed and the data writing was finished.
+  void OnDownloadFinished(int error_code);
+
+  // A list of observers. Weak references.
+  base::ObserverList<DownloadTaskObserver, true> observers_;
+
+  // Back up corresponding public methods of DownloadTask interface.
+  std::unique_ptr<net::URLFetcherResponseWriter> writer_;
+  GURL original_url_;
+  bool is_done_ = false;
+  int error_code_ = 0;
+  int64_t total_bytes_ = -1;
+  int percent_complete_ = -1;
+  std::string content_disposition_;
+  std::string mime_type_;
+
+  const WebState* web_state_ = nullptr;
+  Delegate* delegate_ = nullptr;
+  NSURLSession* session_ = nil;
+  NSURLSessionTask* session_task_ = nil;
+
+  base::WeakPtrFactory<DownloadTaskImpl> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(DownloadTaskImpl);
+};
+
+}  // namespace web
+
+#endif  // IOS_WEB_DOWNLOAD_DOWNLOAD_TASK_IMPL_H_

ios/web/test/fakes/BUILD.gn

@@ -17,6 +17,8 @@ source_set("fakes") {
   sources = [
     "crw_fake_back_forward_list.h",
     "crw_fake_back_forward_list.mm",
+    "crw_fake_nsurl_session_task.h",
+    "crw_fake_nsurl_session_task.mm",
     "fake_navigation_manager_delegate.h",
     "fake_navigation_manager_delegate.mm",
   ]

ios/web/test/fakes/crw_fake_nsurl_session_task.h

+// Copyright 2017 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.
+
+#ifndef IOS_WEB_TEST_FAKES_CRW_FAKE_NSURL_SESSION_TASK_H_
+#define IOS_WEB_TEST_FAKES_CRW_FAKE_NSURL_SESSION_TASK_H_
+
+#import <Foundation/Foundation.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+// Fake NSURLSessionDataTask class which can be used for testing. |cancel| and
+// |resume| methods only change the |state| of this task without actually
+// starting or stopping the download.
+@interface CRWFakeNSURLSessionTask : NSURLSessionDataTask
+
+// Redefined NSURLSessionTask properties as readwrite.
+@property(nonatomic) int64_t countOfBytesReceived;
+@property(nonatomic) int64_t countOfBytesExpectedToReceive;
+@property(nonatomic) NSURLSessionTaskState state;
+
+- (nullable instancetype)initWithURL:(NSURL*)URL NS_DESIGNATED_INITIALIZER;
+- (nullable instancetype)init NS_UNAVAILABLE;
+
+@end
+
+NS_ASSUME_NONNULL_END
+
+#endif  // IOS_WEB_TEST_FAKES_CRW_FAKE_NSURL_SESSION_TASK_H_

ios/web/test/fakes/crw_fake_nsurl_session_task.mm

+// Copyright 2017 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.
+
+#import "ios/web/test/fakes/crw_fake_nsurl_session_task.h"
+
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
+@interface CRWFakeNSURLSessionTask ()
+// NSURLSessionTask properties.
+@property(nullable, readonly, copy) NSURLRequest* originalRequest;
+@property(nullable, readonly, copy) NSURLRequest* currentRequest;
+@end
+
+@implementation CRWFakeNSURLSessionTask
+
+@synthesize countOfBytesReceived = _countOfBytesReceived;
+@synthesize countOfBytesExpectedToReceive = _countOfBytesExpectedToReceive;
+@synthesize state = _state;
+@synthesize originalRequest = _originalRequest;
+@synthesize currentRequest = _currentRequest;
+
+- (instancetype)initWithURL:(NSURL*)URL {
+  if ((self = [super init])) {
+    _state = NSURLSessionTaskStateSuspended;
+    _currentRequest = [NSURLRequest requestWithURL:URL];
+    _originalRequest = [NSURLRequest requestWithURL:URL];
+  }
+  return self;
+}
+
+- (void)cancel {
+  self.state = NSURLSessionTaskStateCanceling;
+}
+- (void)resume {
+  self.state = NSURLSessionTaskStateRunning;
+}
+
+// A private method, called by -[NSHTTPCookieStorage storeCookies:forTask:].
+// Requires stubbing in order to use NSHTTPCookieStorage API.
+- (NSString*)_storagePartitionIdentifier {
+  return nil;
+}
+
+@end