Adding WebContent-free Download

content/browser/download/download_manager_impl.cc

Index: content/browser/download/download_manager_impl.cc
diff --git a/content/browser/download/download_manager_impl.cc b/content/browser/download/download_manager_impl.cc
index 6a98bc2f8a4a1f5e9eae6f63d78d6ee87f2117f6..fb6b06802c8849bf1467f6a88616b6721b0e81f4 100644
--- a/content/browser/download/download_manager_impl.cc
+++ b/content/browser/download/download_manager_impl.cc
@@ -11,6 +11,7 @@
 #include "base/debug/alias.h"
 #include "base/i18n/case_conversion.h"
 #include "base/logging.h"
+#include "base/memory/weak_ptr.h"
 #include "base/message_loop/message_loop.h"
 #include "base/stl_util.h"
 #include "base/strings/stringprintf.h"
@@ -28,7 +29,6 @@
 #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_manager_delegate.h"
@@ -49,8 +49,10 @@
 namespace content {
 namespace {
 
-void BeginDownload(scoped_ptr<DownloadUrlParameters> params,
-                   uint32 download_id) {
+UrlDownloader* BeginDownload(

[asanka, 2015/12/08 21:53:56]

You can return a scoped_ptr<UrlDownloader, DeleteOnIOThread>. That way we won't
leak the object if the task gets dropped on the floor.

It's valid to invoke the default constructor for a scoped_ptr<>. I.e. you can do
scoped_ptr<UrlDownloader>() when you want to return a nullptr. (in case that's
the reason you are returning a raw pointer).

Unfortunately, scoped_ptr<>()s don't atomatically convert to another
scoped_ptr<> type if the deleters aren't implicitly convertible. So you'll need
to repackage the output of UrlDownloader::BeginDownload() into the right
scoped_ptr<> type or have UrlDownloader::BeginDownload() return a
scoped_ptr<UrlDownloader, DeleteOnIOThread>.

Either is OK, but the former is preferable since it assumes that the caller
takes responsibility for deleting the UrlDownloader on the correct thread.

[svaldez, 2015/12/09 17:20:41]

We can't since using PostTask... with a scoped_ptr return type results in a
const scoped_ptr& which prevents us from changing its scope.

[asanka, 2015/12/10 16:27:55]

PostTaskAndReplyWithResult() correctly forwards move only types. The receiving
function can accept a scoped_ptr<>.

+    scoped_ptr<DownloadUrlParameters> params,
+    uint32 download_id,
+    base::WeakPtr<DownloadManagerImpl> download_manager) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   // ResourceDispatcherHost{Base} is-not-a URLRequest::Delegate, and
   // DownloadUrlParameters can-not include resource_dispatcher_host_impl.h, so
@@ -120,19 +122,21 @@ void BeginDownload(scoped_ptr<DownloadUrlParameters> params,
   save_info->prompt_for_save_location = params->prompt();
   save_info->file = params->GetFile();
 
-  ResourceDispatcherHost::Get()->BeginDownload(
-      request.Pass(),
-      params->referrer(),
-      params->content_initiated(),
-      params->resource_context(),
-      params->render_process_host_id(),
-      params->render_view_host_routing_id(),
-      params->render_frame_host_routing_id(),
-      params->prefer_cache(),
-      params->do_not_prompt_for_login(),
-      save_info.Pass(),
-      download_id,
-      params->callback());
+  if (params->render_process_host_id() != -1) {
+    ResourceDispatcherHost::Get()->BeginDownload(
+        request.Pass(), params->referrer(), params->content_initiated(),
+        params->resource_context(), params->render_process_host_id(),
+        params->render_view_host_routing_id(),
+        params->render_frame_host_routing_id(), params->prefer_cache(),
+        params->do_not_prompt_for_login(), save_info.Pass(), download_id,
+        params->callback());
+    return nullptr;
+  }
+  return UrlDownloader::BeginDownload(
+             download_manager, request.Pass(), params->referrer(), false,
+             params->prefer_cache(), true, save_info.Pass(), download_id,
+             params->callback())
+      .release();
 }
 
 class DownloadItemFactoryImpl : public DownloadItemFactory {
@@ -512,10 +516,12 @@ void DownloadManagerImpl::ResumeInterruptedDownload(
     scoped_ptr<content::DownloadUrlParameters> params,
     uint32 id) {
   RecordDownloadSource(INITIATED_BY_RESUMPTION);
-  BrowserThread::PostTask(
-      BrowserThread::IO,
-      FROM_HERE,
-      base::Bind(&BeginDownload, base::Passed(&params), id));
+  BrowserThread::PostTaskAndReplyWithResult(
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(&BeginDownload, base::Passed(&params), id,
+                 weak_factory_.GetWeakPtr()),
+      base::Bind(&DownloadManagerImpl::AddUrlDownloader,
+                 weak_factory_.GetWeakPtr()));
 }
 
 void DownloadManagerImpl::SetDownloadItemFactoryForTesting(
@@ -542,6 +548,23 @@ void DownloadManagerImpl::DownloadRemoved(DownloadItemImpl* download) {
   delete download;
 }
 
+void DownloadManagerImpl::AddUrlDownloader(UrlDownloader* downloader) {
+  if (downloader) {
+    url_downloaders_.push_back(
+        scoped_ptr<UrlDownloader, BrowserThread::DeleteOnIOThread>(downloader));
+  }
+}
+
+void DownloadManagerImpl::RemoveUrlDownloader(UrlDownloader* downloader) {
+  for (auto ptr = url_downloaders_.begin(); ptr != url_downloaders_.end();
+       ++ptr) {
+    if (ptr->get() == downloader) {
+      url_downloaders_.erase(ptr);
+      return;
+    }
+  }
+}
+
 namespace {
 
 bool RemoveDownloadBetween(base::Time remove_begin,
@@ -612,9 +635,12 @@ void DownloadManagerImpl::DownloadUrl(
     DCHECK(params->prefer_cache());
     DCHECK_EQ("POST", params->method());
   }
-  BrowserThread::PostTask(BrowserThread::IO, FROM_HERE, base::Bind(
-      &BeginDownload, base::Passed(&params),
-      content::DownloadItem::kInvalidId));
+  BrowserThread::PostTaskAndReplyWithResult(
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(&BeginDownload, base::Passed(&params),
+                 content::DownloadItem::kInvalidId, weak_factory_.GetWeakPtr()),
+      base::Bind(&DownloadManagerImpl::AddUrlDownloader,
+                 weak_factory_.GetWeakPtr()));
 }
 
 void DownloadManagerImpl::AddObserver(Observer* observer) {