Added A11y announcements for New Download Manager.

The strings has not beed finalized yet, and will be updated in a
separate CL.

Bug: 821188
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: I28e4883e84ec07e003c6a799d7a060640ee41038
Reviewed-on: https://chromium-review.googlesource.com/959589
Commit-Queue: Eugene But <eugenebut@chromium.org>
Reviewed-by: Louis Romero <lpromero@chromium.org>
Cr-Commit-Position: refs/heads/master@{#542802}

ios/chrome/app/strings/ios_strings.grd

@@ -618,6 +618,15 @@ locale.  The strings in this file are specific to iOS.
       <message name="IDS_IOS_DOWNLOAD_MANAGER_UNABLE_TO_OPEN_FILE" desc="Title of dialog displayed when the user attempts to open a downloaded file and no app on the device can open the file. [Length: 25em] [iOS only]">
         Unable to Open File
       </message>
+      <message name="IDS_IOS_DOWNLOAD_MANAGER_FAILED_ACCESSIBILITY_ANNOUNCEMENT" desc="The accessibility announcement read by Voice Over when the download has failed. [Length: unlimited] [iOS only]">
+        Download failed
+      </message>
+      <message name="IDS_IOS_DOWNLOAD_MANAGER_SUCCEEDED_ACCESSIBILITY_ANNOUNCEMENT" desc="The accessibility announcement read by Voice Over when the download has sucessfully finished. [Length: unlimited] [iOS only]">
+        Download successfully finished
+      </message>
+      <message name="IDS_IOS_DOWNLOAD_MANAGER_REQUESTED_ACCESSIBILITY_ANNOUNCEMENT" desc="The accessibility announcement read by Voice Over when the Download Manager UI is shown to the user. [Length: unlimited] [iOS only]">
+        File download is available
+      </message>
       <message name="IDS_IOS_DOWNLOAD_MANAGER_UPLOAD_TO_GOOGLE_DRIVE" desc="Button for uploading a downloaded file to Google Drive. It's displayed on the dialog presented when no app on the device can open the file. [Length: 25em] [iOS only]">
         Upload to Google Drive
       </message>

ios/chrome/browser/ui/download/download_manager_mediator.h

@@ -60,6 +60,10 @@ class DownloadManagerMediator : public web::DownloadTaskObserver {
   // Converts DownloadTask progress [0;100] to float progress [0.0f;1.0f].
   float GetDownloadManagerProgress() const;
 
+  // Returns accessibility announcement for download state change. -1 if there
+  // is no announcement.
+  int GetDownloadManagerA11yAnnouncement() const;
+
   // web::DownloadTaskObserver overrides:
   void OnDownloadUpdated(web::DownloadTask* task) override;
   void OnDownloadDestroyed(web::DownloadTask* task) override;

ios/chrome/browser/ui/download/download_manager_mediator.mm

@@ -4,6 +4,8 @@
 
 #import "ios/chrome/browser/ui/download/download_manager_mediator.h"
 
+#include <UIKit/UIKit.h>
+
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/strings/sys_string_conversions.h"
@@ -11,9 +13,11 @@
 #include "base/task_scheduler/post_task.h"
 #include "ios/chrome/browser/download/download_directory_util.h"
 #import "ios/chrome/browser/download/google_drive_app_util.h"
+#include "ios/chrome/grit/ios_strings.h"
 #import "ios/web/public/download/download_task.h"
 #include "net/base/net_errors.h"
 #include "net/url_request/url_fetcher_response_writer.h"
+#include "ui/base/l10n/l10n_util.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
@@ -108,6 +112,12 @@ void DownloadManagerMediator::UpdateConsumer() {
   [consumer_ setProgress:GetDownloadManagerProgress()];
   [consumer_
       setFileName:base::SysUTF16ToNSString(task_->GetSuggestedFilename())];
+
+  int a11y_announcement = GetDownloadManagerA11yAnnouncement();
+  if (a11y_announcement != -1) {
+    UIAccessibilityPostNotification(UIAccessibilityAnnouncementNotification,
+                                    l10n_util::GetNSString(a11y_announcement));
+  }
 }
 
 DownloadManagerState DownloadManagerMediator::GetDownloadManagerState() const {
@@ -125,6 +135,20 @@ DownloadManagerState DownloadManagerMediator::GetDownloadManagerState() const {
   }
 }
 
+int DownloadManagerMediator::GetDownloadManagerA11yAnnouncement() const {
+  switch (task_->GetState()) {
+    case web::DownloadTask::State::kNotStarted:
+      return IDS_IOS_DOWNLOAD_MANAGER_REQUESTED_ACCESSIBILITY_ANNOUNCEMENT;
+    case web::DownloadTask::State::kComplete:
+      return task_->GetErrorCode()
+                 ? IDS_IOS_DOWNLOAD_MANAGER_FAILED_ACCESSIBILITY_ANNOUNCEMENT
+                 : IDS_IOS_DOWNLOAD_MANAGER_SUCCEEDED_ACCESSIBILITY_ANNOUNCEMENT;
+    case web::DownloadTask::State::kCancelled:
+    case web::DownloadTask::State::kInProgress:
+      return -1;
+  }
+}
+
 float DownloadManagerMediator::GetDownloadManagerProgress() const {
   if (task_->GetPercentComplete() == -1)
     return 0.0f;