Preliminary work on resuming downloads whose connections have expired.

chrome/browser/renderer_host/download_resource_handler.cc

Index: chrome/browser/renderer_host/download_resource_handler.cc
diff --git a/chrome/browser/renderer_host/download_resource_handler.cc b/chrome/browser/renderer_host/download_resource_handler.cc
index 5e83478c97efe4978277b11b96015faec1afe377..9a2c1294dd719d2a7d542b7415b4fc8fbfa9c994 100644
--- a/chrome/browser/renderer_host/download_resource_handler.cc
+++ b/chrome/browser/renderer_host/download_resource_handler.cc
@@ -4,13 +4,16 @@
 
 #include "chrome/browser/renderer_host/download_resource_handler.h"
 
+#include "base/file_util.h"
 #include "base/logging.h"
 #include "chrome/browser/chrome_thread.h"
 #include "chrome/browser/download/download_item.h"
 #include "chrome/browser/download/download_file_manager.h"
+#include "chrome/browser/download/download_util.h"
 #include "chrome/browser/history/download_create_info.h"
 #include "chrome/browser/renderer_host/global_request_id.h"
 #include "chrome/browser/renderer_host/resource_dispatcher_host.h"
+#include "chrome/browser/renderer_host/resource_dispatcher_host_request_info.h"
 #include "chrome/common/resource_response.h"
 #include "net/base/io_buffer.h"
 #include "net/http/http_response_headers.h"
@@ -64,13 +67,26 @@ bool DownloadResourceHandler::OnResponseStarted(int request_id,
   set_content_disposition(content_disposition);
   set_content_length(response->response_head.content_length);
 
-  download_id_ = download_file_manager_->GetNextId();
+  ResourceDispatcherHostRequestInfo* req_info =
+      ResourceDispatcherHost::InfoForRequest(request_);
+  download_id_ = -1;
+  if (req_info->was_interrupted()) {
+    FilePath orig_path = save_info_.file_path;
+    download_id_ = download_file_manager_->GetDownloadId(url_, orig_path);
+    if (download_id_ == -1) {
+      orig_path = download_util::RemoveCrDownloadPath(save_info_.file_path);
+      download_id_ = download_file_manager_->GetDownloadId(url_, orig_path);
+    }
+  }
+  if (download_id_ == -1)
+    download_id_ = download_file_manager_->GetNextId();
   // |download_file_manager_| consumes (deletes):
   DownloadCreateInfo* info = new DownloadCreateInfo;
   info->url = url_;
   info->referrer_url = GURL(request_->referrer());
   info->start_time = base::Time::Now();
-  info->received_bytes = 0;
+  info->received_bytes =
+      req_info->was_interrupted() ? req_info->interrupted_bytes() : 0;
   info->total_bytes = content_length_;
   info->state = DownloadItem::IN_PROGRESS;
   info->download_id = download_id_;
@@ -79,6 +95,37 @@ bool DownloadResourceHandler::OnResponseStarted(int request_id,
   info->request_id = global_id_.request_id;
   info->content_disposition = content_disposition_;
   info->mime_type = response->response_head.mime_type;
+  info->is_partial_download = req_info->was_interrupted();
+
+  // Handle server's response codes.
+  int status = request_->response_headers()->response_code();
+  switch (status) {
+    // Continue with download:
+    case 200:   // OK
+      // Downloading the full file, even if we asked for a range.
+      info->received_bytes = 0;
+      if (info->is_partial_download) {
+        // Delete the crdownload file explicitly.
+        FilePath crpath =
+            download_util::GetCrDownloadPath(save_info_.file_path);
+        file_util::Delete(crpath, false);
+      }
+      // Fall through.
+
+    case 206:   // Partial content.  Leave alone.
+      break;
+
+    case 412:   // Precondition failed.  Fails 'If-Unmodified-Since'.
+    case 204:   // No content.  File not present.
+    default:    // All other errors.
+      // TODO(ahendrickson) -- Cancel, and notify user.
+      break;
+
+    // Retry by downloading from the start automatically:
+    case 416:   // Range not available.  Fails 'Content-Range'.
+      // TODO(ahendrickson) -- Submit another request for the whole file.
+      break;
+  }
 
   std::string content_type_header;
   if (!response->response_head.headers ||
@@ -92,7 +139,8 @@ bool DownloadResourceHandler::OnResponseStarted(int request_id,
   info->referrer_charset = request_->context()->referrer_charset();
   info->save_info = save_info_;
   ChromeThread::PostTask(
-      ChromeThread::UI, FROM_HERE,
+      ChromeThread::UI,
+      FROM_HERE,
       NewRunnableMethod(
           download_file_manager_, &DownloadFileManager::StartDownload, info));
 
@@ -155,12 +203,17 @@ bool DownloadResourceHandler::OnResponseCompleted(
     int request_id,
     const URLRequestStatus& status,
     const std::string& security_info) {
+  int error_code =
+      (status.status() == URLRequestStatus::FAILED) ? status.os_error() : 0;
   ChromeThread::PostTask(
-      ChromeThread::FILE, FROM_HERE,
+      ChromeThread::FILE,
+      FROM_HERE,
       NewRunnableMethod(download_file_manager_,
                         &DownloadFileManager::OnResponseCompleted,
                         download_id_,
-                        buffer_));
+                        buffer_,
+                        error_code,
+                        security_info));
   read_buffer_ = NULL;
 
   // 'buffer_' is deleted by the DownloadFileManager.