Detect removed files and reflect the state in chrome://downloads and the download shelf

chrome/browser/ui/cocoa/download/download_item_cell.mm

Index: chrome/browser/ui/cocoa/download/download_item_cell.mm
diff --git a/chrome/browser/ui/cocoa/download/download_item_cell.mm b/chrome/browser/ui/cocoa/download/download_item_cell.mm
index 234dc10b656424eabfe4d5fbf2ee47d5a679f24c..ccb6e780d138edd76b092339fde9a143f62fdfe5 100644
--- a/chrome/browser/ui/cocoa/download/download_item_cell.mm
+++ b/chrome/browser/ui/cocoa/download/download_item_cell.mm
@@ -87,6 +87,7 @@ const int kInterruptedAnimationDuration = 2.5;
 
 @interface DownloadItemCell(Private)
 - (void)updateTrackingAreas:(id)sender;
+- (void)showSecondaryTitle;
 - (void)hideSecondaryTitle;
 - (void)animation:(NSAnimation*)animation
        progressed:(NSAnimationProgress)progress;
@@ -170,6 +171,7 @@ const int kInterruptedAnimationDuration = 2.5;
     // Set status text.
     NSString* statusString = base::SysUTF16ToNSString(statusText);
     [self setSecondaryTitle:statusString];
+    [self showSecondaryTitle];
     isStatusTextVisible_ = YES;
   }
 
@@ -593,6 +595,10 @@ const int kInterruptedAnimationDuration = 2.5;
                     kImageHeight);
 }
 
+- (void)showSecondaryTitle {
+  [self animation:nil progressed:0.0];
+}
+
 - (void)hideSecondaryTitle {
   if (isStatusTextVisible_) {
     // No core animation -- text in CA layers is not subpixel antialiased :-/