Implement mimetype sniffing for extensions.

chrome/browser/download/download_manager.cc

Index: chrome/browser/download/download_manager.cc
diff --git a/chrome/browser/download/download_manager.cc b/chrome/browser/download/download_manager.cc
index 01ea2d0aa89efd31af3af02b702a1e9a7b54a887..1a3fb53cd6df5b51df56469b42ff113abfa68507 100644
--- a/chrome/browser/download/download_manager.cc
+++ b/chrome/browser/download/download_manager.cc
@@ -117,6 +117,8 @@ DownloadItem::DownloadItem(const DownloadCreateInfo& info)
     : id_(-1),
       full_path_(info.path),
       url_(info.url),
+      referrer_url_(info.referrer_url),
+      mime_type_(info.mime_type),
       total_bytes_(info.total_bytes),
       received_bytes_(info.received_bytes),
       start_tick_(base::TimeTicks()),
@@ -142,6 +144,7 @@ DownloadItem::DownloadItem(int32 download_id,
                            int path_uniquifier,
                            const GURL& url,
                            const GURL& referrer_url,
+                           const std::string& mime_type,
                            const FilePath& original_name,
                            const base::Time start_time,
                            int64 download_size,
@@ -153,6 +156,7 @@ DownloadItem::DownloadItem(int32 download_id,
       path_uniquifier_(path_uniquifier),
       url_(url),
       referrer_url_(referrer_url),
+      mime_type_(mime_type),
       total_bytes_(download_size),
       received_bytes_(0),
       start_tick_(base::TimeTicks::Now()),
@@ -677,6 +681,7 @@ void DownloadManager::ContinueStartDownload(DownloadCreateInfo* info,
                                 info->path_uniquifier,
                                 info->url,
                                 info->referrer_url,
+                                info->mime_type,
                                 info->original_name,
                                 info->start_time,
                                 info->total_bytes,
@@ -841,7 +846,7 @@ void DownloadManager::ContinueDownloadFinished(DownloadItem* download) {
     extension = extension.substr(1);
 
   // Handle chrome extensions explicitly and skip the shell execute.
-  if (Extension::IsExtension(download->full_path())) {
+  if (download->mime_type() == Extension::kMimeType) {
     OpenChromeExtension(download->full_path(), download->url(),
                         download->referrer_url());
     download->set_auto_opened(true);
@@ -1211,7 +1216,7 @@ void DownloadManager::OpenDownload(const DownloadItem* download,
                                    gfx::NativeView parent_window) {
   // Open Chrome extensions with ExtensionsService. For everything else do shell
   // execute.
-  if (Extension::IsExtension(download->full_path())) {
+  if (download->mime_type() == Extension::kMimeType) {
     OpenChromeExtension(download->full_path(), download->url(),
                         download->referrer_url());
   } else {