[Downloads] Allow acquiring dangerous download file.

content/public/browser/download_item.h

Index: content/public/browser/download_item.h
diff --git a/content/public/browser/download_item.h b/content/public/browser/download_item.h
index b3003ef9e8aa3997c6a4e7691bca6d192dec0f63..b32929be3501d8e9c6aceda63d3500b2e0bde8b6 100644
--- a/content/public/browser/download_item.h
+++ b/content/public/browser/download_item.h
@@ -21,6 +21,7 @@
 #include <string>
 #include <vector>
 
+#include "base/callback_forward.h"
 #include "base/files/file_path.h"
 #include "base/string16.h"
 #include "base/supports_user_data.h"
@@ -81,6 +82,9 @@ class CONTENT_EXPORT DownloadItem : public base::SupportsUserData {
                                   // TARGET_DISPOSITION_OVERWRITE.
   };
 
+  // Callback used with AcquireFileAndDeleteDownload().
+  typedef base::Callback<void(const base::FilePath&)> AcquireFileCallback;
+
   static const char kEmptyFileHash[];
 
   // Interface that observers of a particular download must implement in order
@@ -136,6 +140,13 @@ class CONTENT_EXPORT DownloadItem : public base::SupportsUserData {
   // history.
   virtual void Delete(DeleteReason reason) = 0;
 
+  // Acquires the download file and deletes the download. Equivalent to calling
+  // |Delete(DELETE_DUE_TO_USER_DISCARD)| with the exception that the download
+  // file isn't deleted. The path to the file is passed to the |callback|. If
+  // the downloaded file is not available, then returned path will be empty.
+  virtual void AcquireFileAndDeleteDownload(

[Randy Smith (Not in Mondays), 2013/05/23 13:56:43]

What do you think of naming this in some fashion that makes it clear that it's
targeted at dangerous downloads?   

The vision I originally had was having three interfaces
"ValidateDangerousDownload()", "DiscardDangerousDownload()", and
"StealDangerousDownload()".  It's probaby not worthwhile wrapping Delete in
DiscardDangerousDownload, and changing DangerousDownloadValidate's name seems
excessive, but I'd like to nominally associate this with dangerous downloads,
maybe with a DCHECK, so it doesn't get used for other things and so we consider
removing it when/if danger is hoisted up into chrome.

[asanka, 2013/05/23 15:53:31]

How about this?:
- ValidateDangerousDownload()
- StealDangerousDownload()
- Cancel()/Remove()

There'll be no Delete(). It's currently used to discard dangerous downloads,
which could be done by Remove(). The other use is to discard dangerous downloads
during browser shutdown. That can be accomplished by Cancel() instead.

+      const AcquireFileCallback& callback) = 0;
+
   // Removes the download from the views and history.
   virtual void Remove() = 0;