Initial CL for Downloads resumption.

content/browser/download/download_item_impl.cc

 // Copyright (c) 2012 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.
 
 // File method ordering: Methods in this file are in the same order as
 // in download_item_impl.h, with the following exception: The public
 // interface Start is placed in chronological order with the other
 // (private) routines that together define a DownloadItem's state
 // transitions as the download progresses.  See "Download progression
 // cascade" later in this file.
 
 // A regular DownloadItem (created for a download in this session of the
 // browser) normally goes through the following states:
 //      * Created (when download starts)
 //      * Destination filename determined
 //      * Entered into the history database.
 //      * Made visible in the download shelf.
 //      * All the data is saved.  Note that the actual data download occurs
 //        in parallel with the above steps, but until those steps are
 //        complete, the state of the data save will be ignored.
 //      * Download file is renamed to its final name, and possibly
 //        auto-opened.
 
 #include "content/browser/download/download_item_impl.h"
 
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/bind.h"
+#include "base/command_line.h"
 #include "base/file_util.h"
 #include "base/format_macros.h"
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
 #include "base/stl_util.h"
 #include "base/stringprintf.h"
 #include "base/utf_string_conversions.h"
 #include "content/browser/download/download_create_info.h"
 #include "content/browser/download/download_file.h"
 #include "content/browser/download/download_interrupt_reasons_impl.h"
 #include "content/browser/download/download_item_impl_delegate.h"
 #include "content/browser/download/download_request_handle.h"
 #include "content/browser/download/download_stats.h"
+#include "content/browser/renderer_host/render_view_host_impl.h"
 #include "content/browser/web_contents/web_contents_impl.h"
+#include "content/public/browser/browser_context.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/content_browser_client.h"
+#include "content/public/browser/download_interrupt_reasons.h"
+#include "content/public/browser/download_url_parameters.h"
+#include "content/public/common/content_switches.h"
+#include "content/public/common/referrer.h"
 #include "net/base/net_util.h"
 
 namespace content {
+
 namespace {
 
-static void DeleteDownloadedFile(const FilePath& path) {
+void DeleteDownloadedFile(const FilePath& path) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
 
   // Make sure we only delete files.
   if (!file_util::DirectoryExists(path))
     file_util::Delete(path, false);
 }
 
 const char* DebugSafetyStateString(DownloadItem::SafetyState state) {
   switch (state) {
     case DownloadItem::SAFE:
@@ skipping 42 matching lines @@
 
 static void DownloadFileCancel(scoped_ptr<DownloadFile> download_file) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
   download_file->Cancel();
 }
 
 }  // namespace
 
 const char DownloadItem::kEmptyFileHash[] = "";
 
+// The maximum number of attempts we will make to resume automatically.
+const int DownloadItemImpl::kMaxAutoResumeAttempts = 5;
+
 // Constructor for reading from the history service.
 DownloadItemImpl::DownloadItemImpl(DownloadItemImplDelegate* delegate,
                                    DownloadId download_id,
                                    const FilePath& path,
                                    const GURL& url,
                                    const GURL& referrer_url,
                                    const base::Time& start_time,
                                    const base::Time& end_time,
                                    int64 received_bytes,
                                    int64 total_bytes,
@@ skipping 13 matching lines @@
       received_bytes_(received_bytes),
       bytes_per_sec_(0),
       last_reason_(DOWNLOAD_INTERRUPT_REASON_NONE),
       start_tick_(base::TimeTicks()),
       state_(ExternalToInternalState(state)),
       danger_type_(DOWNLOAD_DANGER_TYPE_NOT_DANGEROUS),
       start_time_(start_time),
       end_time_(end_time),
       delegate_(delegate),
       is_paused_(false),
+      auto_resume_count_(0),
       open_when_complete_(false),
       file_externally_removed_(false),
       safety_state_(SAFE),
       auto_opened_(false),
       is_temporary_(false),
       all_data_saved_(false),
       opened_(opened),
       open_enabled_(true),
       delegate_delayed_complete_(false),
       bound_net_log_(bound_net_log),
       ALLOW_THIS_IN_INITIALIZER_LIST(weak_ptr_factory_(this)) {
   delegate_->Attach();
   if (state_ == IN_PROGRESS_INTERNAL)
     state_ = CANCELLED_INTERNAL;
   if (state_ == COMPLETE_INTERNAL)
     all_data_saved_ = true;
   Init(false /* not actively downloading */, SRC_HISTORY_IMPORT);
 }
 
 // Constructing for a regular download:
 DownloadItemImpl::DownloadItemImpl(
     DownloadItemImplDelegate* delegate,
     const DownloadCreateInfo& info,
-    scoped_ptr<DownloadRequestHandleInterface> request_handle,
     const net::BoundNetLog& bound_net_log)
     : is_save_package_download_(false),
-      request_handle_(request_handle.Pass()),
       download_id_(info.download_id),
       target_disposition_(
           (info.save_info->prompt_for_save_location) ?
               TARGET_DISPOSITION_PROMPT : TARGET_DISPOSITION_OVERWRITE),
       url_chain_(info.url_chain),
       referrer_url_(info.referrer_url),
       suggested_filename_(UTF16ToUTF8(info.save_info->suggested_name)),
       forced_file_path_(info.save_info->file_path),
       transition_type_(info.transition_type),
       has_user_gesture_(info.has_user_gesture),
       content_disposition_(info.content_disposition),
       mime_type_(info.mime_type),
       original_mime_type_(info.original_mime_type),
       remote_address_(info.remote_address),
       total_bytes_(info.total_bytes),
       received_bytes_(0),
       bytes_per_sec_(0),
       last_reason_(DOWNLOAD_INTERRUPT_REASON_NONE),
       start_tick_(base::TimeTicks::Now()),
       state_(IN_PROGRESS_INTERNAL),
       danger_type_(DOWNLOAD_DANGER_TYPE_NOT_DANGEROUS),
       start_time_(info.start_time),
       delegate_(delegate),
       is_paused_(false),
+      auto_resume_count_(0),
       open_when_complete_(false),
       file_externally_removed_(false),
       safety_state_(SAFE),
       auto_opened_(false),
       is_temporary_(!info.save_info->file_path.empty()),
       all_data_saved_(false),
       opened_(false),
       open_enabled_(true),
       delegate_delayed_complete_(false),
       bound_net_log_(bound_net_log),
       ALLOW_THIS_IN_INITIALIZER_LIST(weak_ptr_factory_(this)) {
   delegate_->Attach();
-  Init(true /* actively downloading */, SRC_NEW_DOWNLOAD);
+  Init(true /* actively downloading */, SRC_ACTIVE_DOWNLOAD);
 
   // Link the event sources.
   bound_net_log_.AddEvent(
       net::NetLog::TYPE_DOWNLOAD_URL_REQUEST,
       info.request_bound_net_log.source().ToEventParametersCallback());
 
   info.request_bound_net_log.AddEvent(
       net::NetLog::TYPE_DOWNLOAD_STARTED,
       bound_net_log_.source().ToEventParametersCallback());
 }
@@ skipping 20 matching lines @@
       total_bytes_(0),
       received_bytes_(0),
       bytes_per_sec_(0),
       last_reason_(DOWNLOAD_INTERRUPT_REASON_NONE),
       start_tick_(base::TimeTicks::Now()),
       state_(IN_PROGRESS_INTERNAL),
       danger_type_(DOWNLOAD_DANGER_TYPE_NOT_DANGEROUS),
       start_time_(base::Time::Now()),
       delegate_(delegate),
       is_paused_(false),
+      auto_resume_count_(0),
       open_when_complete_(false),
       file_externally_removed_(false),
       safety_state_(SAFE),
       auto_opened_(false),
       is_temporary_(false),
       all_data_saved_(false),
       opened_(false),
       open_enabled_(true),
       delegate_delayed_complete_(false),
       bound_net_log_(bound_net_log),
@@ skipping 53 matching lines @@
       base::Bind(&ItemCheckedNetLogCallback,
                  GetDangerType(), GetSafetyState()));
 
   UpdateObservers();
 
   MaybeCompleteDownload();
 }
 
 void DownloadItemImpl::TogglePause() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  DCHECK(state_ == IN_PROGRESS_INTERNAL || state_ == COMPLETING_INTERNAL);
+  DCHECK(IsPartialDownload());
   VLOG(20) << __FUNCTION__ << " download=" << DebugString(true);
 
   // Ignore pauses when we've passed the commit point.
   if (state_ == COMPLETING_INTERNAL)
     return;
 
-  if (is_paused_)
-    request_handle_->ResumeRequest();
-  else
-    request_handle_->PauseRequest();
-  is_paused_ = !is_paused_;
+  if (IsInProgress()) {
+    if (is_paused_)
+      request_handle_->ResumeRequest();
+    else
+      request_handle_->PauseRequest();
+    is_paused_ = !is_paused_;
+  } else if (IsInterrupted()) {
+    auto_resume_count_ = 0;  // User input resets the counter.
+    ResumeInterruptedDownload();
+  }
+
   UpdateObservers();

[benjhayden, 2013/01/06 15:46:04]

Do we want to UpdateObservers even if !IsInProgress() && !IsInterrupted()?

[Randy Smith (Not in Mondays), 2013/01/07 20:54:10]

Good point; done.

 }
 
 void DownloadItemImpl::Cancel(bool user_cancel) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
-  last_reason_ = user_cancel ?
-      DOWNLOAD_INTERRUPT_REASON_USER_CANCELED :
-      DOWNLOAD_INTERRUPT_REASON_USER_SHUTDOWN;
-
   VLOG(20) << __FUNCTION__ << "() download = " << DebugString(true);
-  if (state_ != IN_PROGRESS_INTERNAL) {
+  if (state_ != IN_PROGRESS_INTERNAL && state_ != INTERRUPTED_INTERNAL) {
     // Small downloads might be complete before this method has
     // a chance to run.
     return;
   }
 
+  last_reason_ = user_cancel ?
+      DOWNLOAD_INTERRUPT_REASON_USER_CANCELED :
+      DOWNLOAD_INTERRUPT_REASON_USER_SHUTDOWN;
+
   RecordDownloadCount(CANCELLED_COUNT);
 
   TransitionTo(CANCELLED_INTERNAL);
 
   CancelDownloadFile();
 
   // Cancel the originating URL request.
   request_handle_->CancelRequest();
 }
 
 void DownloadItemImpl::Delete(DeleteReason reason) {
+  VLOG(20) << __FUNCTION__ << "() download = " << DebugString(true);
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   switch (reason) {
     case DELETE_DUE_TO_USER_DISCARD:
       UMA_HISTOGRAM_ENUMERATION(
           "Download.UserDiscard", GetDangerType(),
           DOWNLOAD_DANGER_TYPE_MAX);
       break;
     case DELETE_DUE_TO_BROWSER_SHUTDOWN:
       UMA_HISTOGRAM_ENUMERATION(
           "Download.Discard", GetDangerType(),
           DOWNLOAD_DANGER_TYPE_MAX);
       break;
     default:
       NOTREACHED();
   }
 
   // Delete the file if it exists and is not owned by a DownloadFile object.
   // (In the latter case the DownloadFile object will delete it on cancel.)
   if (!current_path_.empty() && download_file_.get() == NULL) {
     BrowserThread::PostTask(BrowserThread::FILE, FROM_HERE,
                             base::Bind(&DeleteDownloadedFile, current_path_));
   }
   Remove();
   // We have now been deleted.
 }
 
 void DownloadItemImpl::Remove() {
+  VLOG(20) << __FUNCTION__ << "() download = " << DebugString(true);
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   delegate_->AssertStateConsistent(this);
   Cancel(true);
   delegate_->AssertStateConsistent(this);
 
   NotifyRemoved();
   delegate_->DownloadRemoved(this);
   // We have now been deleted.
 }
@@ skipping 53 matching lines @@
 }
 
 bool DownloadItemImpl::IsPaused() const {
   return is_paused_;
 }
 
 bool DownloadItemImpl::IsTemporary() const {
   return is_temporary_;
 }
 
-// TODO(ahendrickson) -- Move |INTERRUPTED| from |IsCancelled()| to
-// |IsPartialDownload()|, when resuming interrupted downloads is implemented.
 bool DownloadItemImpl::IsPartialDownload() const {
-  return InternalToExternalState(state_) == IN_PROGRESS;
+  DownloadState state = InternalToExternalState(state_);
+  return (state == IN_PROGRESS) || (state == INTERRUPTED);
 }
 
 bool DownloadItemImpl::IsInProgress() const {
   return InternalToExternalState(state_) == IN_PROGRESS;
 }
 
 bool DownloadItemImpl::IsCancelled() const {
-  DownloadState external_state = InternalToExternalState(state_);
-  return  external_state == CANCELLED || external_state == INTERRUPTED;
+  return  InternalToExternalState(state_) == CANCELLED;
 }
 
 bool DownloadItemImpl::IsInterrupted() const {
   return InternalToExternalState(state_) == INTERRUPTED;
 }
 
 bool DownloadItemImpl::IsComplete() const {
   return InternalToExternalState(state_) == COMPLETE;
 }
 
@@ skipping 255 matching lines @@
       url_list += next_url.spec();
     }
   }
 
   if (verbose) {
     description += base::StringPrintf(
         " total = %" PRId64
         " received = %" PRId64
         " reason = %s"
         " paused = %c"
+        " resume_mode = %s"
+        " auto_resume_count = %d"
         " safety = %s"
+        " all_data_saved = %c"
         " last_modified = '%s'"
         " etag = '%s'"
+        " has_download_file = %s"
         " url_chain = \n\t\"%s\"\n\t"
-        " full_path = \"%" PRFilePath "\""
-        " target_path = \"%" PRFilePath "\""
-        " has download file = %s",
+        " full_path = \"%" PRFilePath "\"\n\t"
+        " target_path = \"%" PRFilePath "\"",
         GetTotalBytes(),
         GetReceivedBytes(),
         InterruptReasonDebugString(last_reason_).c_str(),
         IsPaused() ? 'T' : 'F',
+        DebugResumeModeString(GetResumeMode()),
+        auto_resume_count_,
         DebugSafetyStateString(GetSafetyState()),
+        AllDataSaved() ? 'T' : 'F',
         GetLastModifiedTime().c_str(),
         GetETag().c_str(),
+        download_file_.get() ? "true" : "false",
         url_list.c_str(),
         GetFullPath().value().c_str(),
-        GetTargetFilePath().value().c_str(),
-        download_file_.get() ? "true" : "false");
+        GetTargetFilePath().value().c_str());
   } else {
     description += base::StringPrintf(" url = \"%s\"", url_list.c_str());
   }
 
   description += " }";
 
   return description;
 }
 
 void DownloadItemImpl::MockDownloadOpenForTesting() {
   open_enabled_ = false;
 }
 
+DownloadItemImpl::ResumeMode DownloadItemImpl::GetResumeMode() const {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  if (!IsInterrupted())
+    return RESUME_MODE_INVALID;
+
+  ResumeMode mode = RESUME_MODE_INVALID;
+
+  switch(last_reason_) {
+    case DOWNLOAD_INTERRUPT_REASON_FILE_TRANSIENT_ERROR:
+    case DOWNLOAD_INTERRUPT_REASON_NETWORK_TIMEOUT:
+      mode = RESUME_MODE_IMMEDIATE_CONTINUE;  // Continue immediately.

[benjhayden, 2013/01/06 15:46:04]

These comments look unnecessary.

[Randy Smith (Not in Mondays), 2013/01/07 20:54:10]

Done.

+      break;
+
+    case DOWNLOAD_INTERRUPT_REASON_SERVER_PRECONDITION:
+    case DOWNLOAD_INTERRUPT_REASON_SERVER_NO_RANGE:
+    case DOWNLOAD_INTERRUPT_REASON_FILE_TOO_SHORT:
+      mode = RESUME_MODE_IMMEDIATE_RESTART;  // Restart immediately.
+      break;
+
+    case DOWNLOAD_INTERRUPT_REASON_NETWORK_FAILED:
+    case DOWNLOAD_INTERRUPT_REASON_NETWORK_DISCONNECTED:
+    case DOWNLOAD_INTERRUPT_REASON_NETWORK_SERVER_DOWN:
+    case DOWNLOAD_INTERRUPT_REASON_SERVER_FAILED:
+    case DOWNLOAD_INTERRUPT_REASON_USER_SHUTDOWN:
+    case DOWNLOAD_INTERRUPT_REASON_CRASH:
+      mode = RESUME_MODE_USER_CONTINUE;  // Continue via user input.
+      break;
+
+    case DOWNLOAD_INTERRUPT_REASON_FILE_FAILED:
+    case DOWNLOAD_INTERRUPT_REASON_FILE_ACCESS_DENIED:
+    case DOWNLOAD_INTERRUPT_REASON_FILE_NO_SPACE:
+    case DOWNLOAD_INTERRUPT_REASON_FILE_NAME_TOO_LONG:
+    case DOWNLOAD_INTERRUPT_REASON_FILE_TOO_LARGE:
+      mode = RESUME_MODE_USER_RESTART;  // Restart via user input.
+      break;
+
+    case DOWNLOAD_INTERRUPT_REASON_NONE:
+    case DOWNLOAD_INTERRUPT_REASON_FILE_VIRUS_INFECTED:
+    case DOWNLOAD_INTERRUPT_REASON_SERVER_BAD_CONTENT:
+    case DOWNLOAD_INTERRUPT_REASON_USER_CANCELED:
+      break;

[benjhayden, 2013/01/06 15:46:04]

Merge this fall-through with the next?
Maybe explicitly set mode = INVALID for clarity so we don't need to scroll up to
double-check the default value?
"default:" switch case?

[Randy Smith (Not in Mondays), 2013/01/07 20:54:10]

Done.

+
+    case DOWNLOAD_INTERRUPT_REASON_FILE_BLOCKED:
+    case DOWNLOAD_INTERRUPT_REASON_FILE_SECURITY_CHECK_FAILED:
+      break;
+  }
+
+  // If we don't have a file name, we won't be able to continue the
+  // download (e.g. if we're interrupted before intermediate rename).
+  if (current_path_.empty()) {
+    if (mode == RESUME_MODE_USER_CONTINUE)
+      mode = RESUME_MODE_USER_RESTART;

[benjhayden, 2013/01/06 15:46:04]

How would you feel about trying to merge these exceptions into the switch so
that we only have to look at 1 place to figure out why mode is a given value?

[Randy Smith (Not in Mondays), 2013/01/07 20:54:10]

This was an amusing exercise in "what's the simplest code to read?" :-}.  Some
of the logic is still pulled out (I didn't want to duplicate even semi-complex
logic) but there are obvious breadcrumbs.  Let me know what you think.

+    if (mode == RESUME_MODE_IMMEDIATE_CONTINUE)

[benjhayden, 2013/01/06 15:46:04]

else if

[Randy Smith (Not in Mondays), 2013/01/07 20:54:10]

Moot.  

+      mode = RESUME_MODE_IMMEDIATE_RESTART;
+  }
+
+  // Check if we have exhausted the number of automatic retry attempts.
+  // We also force user interaction if the user previously paused the
+  // download.
+  if (auto_resume_count_ >= kMaxAutoResumeAttempts || is_paused_) {
+    if (mode == RESUME_MODE_IMMEDIATE_CONTINUE)
+      mode = RESUME_MODE_USER_CONTINUE;
+    else if (mode == RESUME_MODE_IMMEDIATE_RESTART)
+      mode = RESUME_MODE_USER_RESTART;
+  }
+
+  return mode;
+}
+
+void DownloadItemImpl::ResumeInterruptedDownload() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  // If the flag for downloads resumption isn't enabled, ignore

[benjhayden, 2013/01/06 15:46:04]

Would it make more sense to just not show the resume button in this case? It
seems strange to sometimes quietly ignore requests depending on a flag.

[Randy Smith (Not in Mondays), 2013/01/07 20:54:10]

"Do not try to tweak the resume button.  Only try to realize the truth; there is
no resume button." 

This CL specifically has the UI aspects taken out of it (they're in 11673003,
and I've done nothing with them--Asanka will add what he thinks the right UI is
later).  So the only thing that calls this routine is tests.  So the question is
"What's the right content interface for resumption?"  My judgement was that
ignoring resumption requests if we aren't enabled for resumption was the right
interface.  

+  // this request.
+  const CommandLine& command_line = *CommandLine::ForCurrentProcess();
+  if (!command_line.HasSwitch(switches::kEnableDownloadResumption))
+    return;
+
+  // Handle the case of clicking 'Resume' in the download shelf.
+  DCHECK(IsInterrupted());
+
+  DVLOG(20) << __FUNCTION__ << "()" << DebugString(true);
+
+  // If we can't get a web contents, we can't resume the download.
+  // TODO(rdsmith): Find some alternative web contents to use--this
+  // means we can't restart a download if it's a download imported
+  // from the history.
+  if (!GetWebContents())
+    return;
+
+  // Reset the apporpriate state if restarting.

[benjhayden, 2013/01/06 15:46:04]

"appROpriate", and at least one of this comment and the next seem unnecessary.

[Randy Smith (Not in Mondays), 2013/01/07 20:54:10]

Done.

+  ResumeMode mode = GetResumeMode();
+  if (mode == RESUME_MODE_IMMEDIATE_RESTART ||
+      mode == RESUME_MODE_USER_RESTART) {
+    received_bytes_ = 0;  // Restart instead of continuing.
+    hash_state_ = "";
+    last_modified_time_ = "";
+    etag_ = "";
+  }
+
+  scoped_ptr<DownloadUrlParameters> download_params(
+      DownloadUrlParameters::FromWebContents(GetWebContents(),
+                                             GetOriginalUrl()));
+
+  download_params->set_file_path(GetFullPath());
+  download_params->set_offset(GetReceivedBytes());
+  download_params->set_hash_state(GetHashState());
+
+  Referrer referrer(GetReferrerUrl(), WebKit::WebReferrerPolicyDefault);
+  download_params->set_referrer(referrer);
+  download_params->set_last_modified(GetLastModifiedTime());
+  download_params->set_etag(GetETag());
+  download_params->set_callback(DownloadUrlParameters::OnStartedCallback());
+
+  delegate_->ResumeInterruptedDownload(download_params.Pass(), GetGlobalId());

[benjhayden, 2013/01/06 15:46:04]

Should the id be inside DownloadUrlParams?
Why use the global id instead of the local id?

[Randy Smith (Not in Mondays), 2013/01/07 20:54:10]

I was going to make some vague statements based on instinct, but a more solid
argument: I really don't think the id should be part of the interface to
DownloadManager::DownloadUrl().  It's meaning is subtle (invalid -> create new,
existing -> resume if exists, (eventually) start with that id if it doesn't
exist)), and not really appropriate for non-download system folks to specify.
Hmmm.  I didn't think about it.  As you know, I'd like to get rid of the global
id everywhere outside of the DownloadPathReservationTracker.  So I guess it
might make sense to take it out.  The path does go outside of the "profile",
though (through resource dispatcher host impl) so given that we have two types
of id, the global one could be argued to be the right one.  But I don't have
strong feelings here, other than laziness and not wanting to do the replumbing
in the CL.  But if it's something you care about, I'm happy to switch it. 
What's your preference?

+
+  // Just in case we were interrupted while paused.
+  is_paused_ = false;
+}
+
 void DownloadItemImpl::NotifyRemoved() {
   FOR_EACH_OBSERVER(Observer, observers_, OnDownloadRemoved(this));
 }
 
 void DownloadItemImpl::OnDownloadedFileRemoved() {
   file_externally_removed_ = true;
   VLOG(20) << __FUNCTION__ << " download=" << DebugString(true);
   UpdateObservers();
 }
 
 base::WeakPtr<DownloadDestinationObserver>
 DownloadItemImpl::DestinationObserverAsWeakPtr() {
   return weak_ptr_factory_.GetWeakPtr();
 }
 
+const net::BoundNetLog& DownloadItemImpl::GetBoundNetLog() const {
+  return bound_net_log_;
+}
+
 void DownloadItemImpl::SetTotalBytes(int64 total_bytes) {
   total_bytes_ = total_bytes;
 }
 
 // Updates from the download thread may have been posted while this download
 // was being cancelled in the UI thread, so we'll accept them unless we're
 // complete.
 void DownloadItemImpl::UpdateProgress(int64 bytes_so_far,
                                       int64 bytes_per_sec,
                                       const std::string& hash_state) {
@@ skipping 136 matching lines @@
         net::NetLog::TYPE_DOWNLOAD_ITEM_ACTIVE, active_data);
   } else {
     bound_net_log_.AddEvent(
         net::NetLog::TYPE_DOWNLOAD_ITEM_ACTIVE, active_data);
   }
 
   VLOG(20) << __FUNCTION__ << "() " << DebugString(true);
 }
 
 // We're starting the download.
-void DownloadItemImpl::Start(scoped_ptr<DownloadFile> file) {
+void DownloadItemImpl::Start(
+    scoped_ptr<DownloadFile> file,
+    scoped_ptr<DownloadRequestHandleInterface> req_handle) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   DCHECK(!download_file_.get());
   DCHECK(file.get());
+  DCHECK(req_handle.get());
+
   download_file_ = file.Pass();
+  request_handle_ = req_handle.Pass();
+
+  TransitionTo(IN_PROGRESS_INTERNAL);
+
+  last_reason_ = DOWNLOAD_INTERRUPT_REASON_NONE;
 
   BrowserThread::PostTask(
       BrowserThread::FILE, FROM_HERE,
       base::Bind(&DownloadFile::Initialize,
                  // Safe because we control download file lifetime.
                  base::Unretained(download_file_.get()),
                  base::Bind(&DownloadItemImpl::OnDownloadFileInitialized,
                             weak_ptr_factory_.GetWeakPtr())));
 }
 
 void DownloadItemImpl::OnDownloadFileInitialized(
     DownloadInterruptReason result) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   if (result != DOWNLOAD_INTERRUPT_REASON_NONE) {
     Interrupt(result);
     // TODO(rdsmith): It makes no sense to continue along the
     // regular download path after we've gotten an error.  But it's
     // the way the code has historically worked, and this allows us
     // to get the download persisted and observers of the download manager
     // notified, so tests work.  When we execute all side effects of cancel
-    // (including queue removal) immedately rather than waiting for
+    // (including queue removal) immediately rather than waiting for
     // persistence we should replace this comment with a "return;".
   }
 
+  // If we're resuming an interrupted download, we may already know
+  // the download target so we can skip target name determination.
+  if (!GetTargetFilePath().empty() && !GetFullPath().empty()) {
+    delegate_->ShowDownloadInBrowser(this);
+    MaybeCompleteDownload();
+    return;
+  }
+
+  // The target path might be set and the full path empty if we failed
+  // the intermediate rename--re-do file name determination in this case.
+  // TODO(rdsmith,asanka): Clean up this logic.
+  target_path_ = FilePath();
+
   delegate_->DetermineDownloadTarget(
       this, base::Bind(&DownloadItemImpl::OnDownloadTargetDetermined,
                        weak_ptr_factory_.GetWeakPtr()));
 }
 
 // Called by delegate_ when the download target path has been
 // determined.
 void DownloadItemImpl::OnDownloadTargetDetermined(
     const FilePath& target_path,
     TargetDisposition disposition,
     DownloadDangerType danger_type,
     const FilePath& intermediate_path) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   // If the |target_path| is empty, then we consider this download to be
   // canceled.
   if (target_path.empty()) {
     Cancel(true);
     return;
   }
 
+  // TODO(rdsmith,asanka): We are ignoring the possibility that the download
+  // has been interrupted at this point until we finish the intermediate
+  // rename and set the full path.  That's dangerous, because we might race
+  // with resumption, either manual (because the interrupt is visible to the
+  // UI) or automatic.  If we keep the "ignore an error on download until file
+  // name determination complete" semantics, we need to make sure that the
+  // error is kept completely invisible until that point.
+
   VLOG(20) << __FUNCTION__ << " " << target_path.value() << " " << disposition
            << " " << danger_type << " " << DebugString(true);
 
   target_path_ = target_path;
   target_disposition_ = disposition;
   SetDangerType(danger_type);
   // TODO(asanka): SetDangerType() doesn't need to send a notification here.
 
   // We want the intermediate and target paths to refer to the same directory so
   // that they are both on the same device and subject to same
   // space/permission/availability constraints.
   DCHECK(intermediate_path.DirName() == target_path.DirName());
 
-  if (state_ != IN_PROGRESS_INTERNAL) {
-    // If we've been cancelled or interrupted while the target was being
-    // determined, continue the cascade with a null name.
-    // The error doesn't matter as the cause of download stoppage
-    // will already have been recorded and will be retained, but we use
-    // whatever was recorded for consistency.
-    OnDownloadRenamedToIntermediateName(last_reason_, FilePath());
-    return;
-  }
-
   // Rename to intermediate name.
   // TODO(asanka): Skip this rename if AllDataSaved() is true. This avoids a
   //               spurious rename when we can just rename to the final
   //               filename. Unnecessary renames may cause bugs like
   //               http://crbug.com/74187.
   DCHECK(!is_save_package_download_);
   DCHECK(download_file_.get());
   DownloadFile::RenameCompletionCallback callback =
       base::Bind(&DownloadItemImpl::OnDownloadRenamedToIntermediateName,
                  weak_ptr_factory_.GetWeakPtr());
@@ skipping 56 matching lines @@
   if (state_ != IN_PROGRESS_INTERNAL)
     return;
 
   // Give the delegate a chance to override.
   delegate_->ReadyForDownloadCompletion(
       this, base::Bind(&DownloadItemImpl::ReadyForDownloadCompletionDone,
                        weak_ptr_factory_.GetWeakPtr()));
 }
 
 void DownloadItemImpl::ReadyForDownloadCompletionDone() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
   if (state_ != IN_PROGRESS_INTERNAL)
     return;
 
-  VLOG(20) << __FUNCTION__ << "()"
-           << " " << DebugString(true);
+  VLOG(20) << __FUNCTION__ << "()" << " " << DebugString(true);
   DCHECK(!GetTargetFilePath().empty());
   DCHECK_NE(DANGEROUS, GetSafetyState());
 
   // TODO(rdsmith/benjhayden): Remove as part of SavePackage integration.
   if (is_save_package_download_) {
     // Avoid doing anything on the file thread; there's nothing we control
     // there.
     // Strictly speaking, this skips giving the embedder a chance to open
     // the download.  But on a save package download, there's no real
     // concept of opening.
@@ skipping 58 matching lines @@
   if (delegate_->ShouldOpenDownload(
           this, base::Bind(&DownloadItemImpl::DelayedDownloadOpened,
                            weak_ptr_factory_.GetWeakPtr()))) {
     Completed();
   } else {
     delegate_delayed_complete_ = true;
   }
 }
 
 void DownloadItemImpl::DelayedDownloadOpened(bool auto_opened) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
   auto_opened_ = auto_opened;
   Completed();
 }
 
 void DownloadItemImpl::Completed() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   VLOG(20) << __FUNCTION__ << "() " << DebugString(false);
 
   DCHECK(all_data_saved_);
@@ skipping 14 matching lines @@
 
     auto_opened_ = true;
     UpdateObservers();
   }
 }
 
 // **** End of Download progression cascade
 
 // An error occurred somewhere.
 void DownloadItemImpl::Interrupt(DownloadInterruptReason reason) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
   // Somewhat counter-intuitively, it is possible for us to receive an
   // interrupt after we've already been interrupted.  The generation of
   // interrupts from the file thread Renames and the generation of
   // interrupts from disk writes go through two different mechanisms (driven
   // by rename requests from UI thread and by write requests from IO thread,
   // respectively), and since we choose not to keep state on the File thread,
   // this is the place where the races collide.  It's also possible for
   // interrupts to race with cancels.
 
   // Whatever happens, the first one to hit the UI thread wins.
   if (state_ != IN_PROGRESS_INTERNAL)
     return;
 
   last_reason_ = reason;
+
   TransitionTo(INTERRUPTED_INTERNAL);
 
-  CancelDownloadFile();
+  ResumeMode resume_mode = GetResumeMode();
+  if (resume_mode == RESUME_MODE_IMMEDIATE_RESTART ||
+      resume_mode == RESUME_MODE_USER_RESTART) {
+    // Remove the download file; no point in leaving data around we
+    // aren't going to use.
+    CancelDownloadFile();
+  } else {
+    // Keep the file around and maybe re-use it.
+    BrowserThread::PostTask(
+        BrowserThread::FILE, FROM_HERE,
+        base::Bind(&DownloadFileDetach, base::Passed(&download_file_)));
+  }
 
   // Cancel the originating URL request.
   request_handle_->CancelRequest();
 
   RecordDownloadInterrupted(reason, received_bytes_, total_bytes_);
+  AutoResumeIfValid();
 }
 
 void DownloadItemImpl::CancelDownloadFile() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
   // TODO(rdsmith/benjhayden): Remove condition as part of
-  // SavePackage integration.
-  // download_file_ can be NULL if Interrupt() is called after the download file
-  // has been released.
+  // |SavePackage| integration.
+  // |download_file_| can be NULL if Interrupt() is called after the
+  // download file has been released.
   if (!is_save_package_download_ && download_file_.get()) {
     BrowserThread::PostTask(
         BrowserThread::FILE, FROM_HERE,
         // Will be deleted at end of task execution.
         base::Bind(&DownloadFileCancel, base::Passed(&download_file_)));
   }
 }
 
 bool DownloadItemImpl::IsDownloadReadyForCompletion() {
   VLOG(20) << __FUNCTION__ << " " << AllDataSaved()
            << " " << (GetSafetyState() != DownloadItem::DANGEROUS)
            << " " << (state_ == IN_PROGRESS_INTERNAL)
            << " " << !GetTargetFilePath().empty()
            << " " << (target_path_.DirName() == current_path_.DirName());
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
   // If we don't have all the data, the download is not ready for
   // completion.
   if (!AllDataSaved())
     return false;
 
   // If the download is dangerous, but not yet validated, it's not ready for
   // completion.
   if (GetSafetyState() == DownloadItem::DANGEROUS)
     return false;
 
   // If the download isn't active (e.g. has been cancelled) it's not
   // ready for completion.
   if (state_ != IN_PROGRESS_INTERNAL)
     return false;
 
   // If the target filename hasn't been determined, then it's not ready for
   // completion. This is checked in ReadyForDownloadCompletionDone().
   if (GetTargetFilePath().empty())
     return false;
 
   // This is checked in NeedsRename(). Without this conditional,
   // browser_tests:DownloadTest.DownloadMimeType fails the DCHECK.
   if (target_path_.DirName() != current_path_.DirName())
     return false;
 
   return true;
 }
 
 void DownloadItemImpl::TransitionTo(DownloadInternalState new_state) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
   if (state_ == new_state)
     return;
 
   DownloadInternalState old_state = state_;
   state_ = new_state;
 
   switch (state_) {
     case COMPLETING_INTERNAL:
       bound_net_log_.AddEvent(
           net::NetLog::TYPE_DOWNLOAD_ITEM_COMPLETING,
           base::Bind(&ItemCompletingNetLogCallback, received_bytes_, &hash_));
       break;
     case COMPLETE_INTERNAL:
       bound_net_log_.AddEvent(
           net::NetLog::TYPE_DOWNLOAD_ITEM_FINISHED,
           base::Bind(&ItemFinishedNetLogCallback, auto_opened_));
       break;
     case INTERRUPTED_INTERNAL:
       bound_net_log_.AddEvent(
           net::NetLog::TYPE_DOWNLOAD_ITEM_INTERRUPTED,
           base::Bind(&ItemInterruptedNetLogCallback, last_reason_,
                      received_bytes_, &hash_state_));
       break;
+    case IN_PROGRESS_INTERNAL:
+      if (old_state == INTERRUPTED_INTERNAL) {
+        bound_net_log_.AddEvent(
+            net::NetLog::TYPE_DOWNLOAD_ITEM_RESUMED,
+            base::Bind(&ItemResumingNetLogCallback,
+                       false, last_reason_, received_bytes_, &hash_state_));
+      }
+      break;
     case CANCELLED_INTERNAL:
       bound_net_log_.AddEvent(
           net::NetLog::TYPE_DOWNLOAD_ITEM_CANCELED,
           base::Bind(&ItemCanceledNetLogCallback, received_bytes_,
                      &hash_state_));
       break;
     default:
       break;
   }
 
   VLOG(20) << " " << __FUNCTION__ << "()" << " this = " << DebugString(true)
     << " " << InternalToExternalState(old_state)
     << " " << InternalToExternalState(state_);
 
   // Only update observers on user visible state changes.
-  if (InternalToExternalState(old_state) != InternalToExternalState(state_))
+  if (InternalToExternalState(state_) != InternalToExternalState(old_state))
     UpdateObservers();
 
   bool is_done = (state_ != IN_PROGRESS_INTERNAL &&
                   state_ != COMPLETING_INTERNAL);
   bool was_done = (old_state != IN_PROGRESS_INTERNAL &&
                    old_state != COMPLETING_INTERNAL);
+  // Termination
   if (is_done && !was_done)
     bound_net_log_.EndEvent(net::NetLog::TYPE_DOWNLOAD_ITEM_ACTIVE);
+
+  // Resumption
+  if (was_done && !is_done) {
+    std::string file_name(target_path_.BaseName().AsUTF8Unsafe());
+    bound_net_log_.BeginEvent(net::NetLog::TYPE_DOWNLOAD_ITEM_ACTIVE,
+                              base::Bind(&ItemActivatedNetLogCallback,
+                                         this, SRC_ACTIVE_DOWNLOAD,
+                                         &file_name));
+  }
 }
 
 void DownloadItemImpl::SetDangerType(DownloadDangerType danger_type) {
   danger_type_ = danger_type;
   // Notify observers if the safety state has changed as a result of the new
   // danger type.
   SafetyState updated_value = IsDangerous() ?
       DownloadItem::DANGEROUS : DownloadItem::SAFE;
   if (updated_value != safety_state_) {
     safety_state_ = updated_value;
@@ skipping 12 matching lines @@
   DCHECK(!new_path.empty());
 
   bound_net_log_.AddEvent(
       net::NetLog::TYPE_DOWNLOAD_ITEM_RENAMED,
       base::Bind(&ItemRenamedNetLogCallback, &current_path_, &new_path));
 
   current_path_ = new_path;
   UpdateObservers();
 }
 
+void DownloadItemImpl::AutoResumeIfValid() {
+  DVLOG(20) << __FUNCTION__ << "() " << DebugString(true);
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  ResumeMode mode = GetResumeMode();
+
+  if (mode != RESUME_MODE_IMMEDIATE_RESTART &&
+      mode != RESUME_MODE_IMMEDIATE_CONTINUE) {
+    return;
+  }
+
+  auto_resume_count_++;
+
+  ResumeInterruptedDownload();
+}
+
 // static
 DownloadItem::DownloadState DownloadItemImpl::InternalToExternalState(
     DownloadInternalState internal_state) {
   switch (internal_state) {
     case IN_PROGRESS_INTERNAL:
       return IN_PROGRESS;
     case COMPLETING_INTERNAL:
       return IN_PROGRESS;
     case COMPLETE_INTERNAL:
       return COMPLETE;
@@ skipping 38 matching lines @@
     case CANCELLED_INTERNAL:
       return "CANCELLED";
     case INTERRUPTED_INTERNAL:
       return "INTERRUPTED";
     default:
       NOTREACHED() << "Unknown download state " << state;
       return "unknown";
   };
 }
 
+const char* DownloadItemImpl::DebugResumeModeString(ResumeMode mode) {
+  switch (mode) {
+    case RESUME_MODE_INVALID:
+      return "INVALID";
+    case RESUME_MODE_IMMEDIATE_CONTINUE:
+      return "IMMEDIATE_CONTINUE";
+    case RESUME_MODE_IMMEDIATE_RESTART:
+      return "IMMEDIATE_RESTART";
+    case RESUME_MODE_USER_CONTINUE:
+      return "USER_CONTINUE";
+    case RESUME_MODE_USER_RESTART:
+      return "USER_RESTART";
+  }
+  NOTREACHED() << "Unknown resume mode " << mode;
+  return "unknown";
+}
+
 }  // namespace content