downloads: clicking "remove" on chrome://downloads should also hide shelf item.

chrome/browser/download/download_shelf.h

Index: chrome/browser/download/download_shelf.h
diff --git a/chrome/browser/download/download_shelf.h b/chrome/browser/download/download_shelf.h
index a42042f06efdf2251b0765fa1a1a8a9366caf4be..acc7708e1a50934c0ae85e87c8f92c62dd047cfa 100644
--- a/chrome/browser/download/download_shelf.h
+++ b/chrome/browser/download/download_shelf.h
@@ -135,6 +135,17 @@ class DownloadShelf {
   // before the delay duration, it will not be added to the shelf at all.
   void AddDownload(content::DownloadItem* download);
 
+  // Remove |download| from our shelf if it exists.
+  //
+  // NOTE: This call is only necessary if |download| needs to be hidden but
+  // isn't actually being deleted. For example: a download is visually hidden
+  // from chrome://downloads but isn't deleted until the page closes (so the
+  // removal can be undone).
+  //
+  // To really remove a download from all views and delete any intermediate
+  // files, call DownloadItem::Remove().
+  virtual void RemoveDownload(content::DownloadItem* download) = 0;
+
   // The browser view needs to know when we are going away to properly return
   // the resize corner size to WebKit so that we don't draw on top of it.
   // This returns the showing state of our animation which is set to true at