Added download error descriptions to tooltips for Mac & Linux.

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

Index: chrome/browser/ui/cocoa/download/download_item_controller.mm
diff --git a/chrome/browser/ui/cocoa/download/download_item_controller.mm b/chrome/browser/ui/cocoa/download/download_item_controller.mm
index faac76d7ef690268f108ad453d8df683d24d9334..22bf80c5f63d45b531e78a2135bda1606496093d 100644
--- a/chrome/browser/ui/cocoa/download/download_item_controller.mm
+++ b/chrome/browser/ui/cocoa/download/download_item_controller.mm
@@ -44,6 +44,7 @@ const int kTextWidth = 140;            // Pixels
 
 // The maximum width in pixels for the file name tooltip.
 const int kToolTipMaxWidth = 900;
+const int kToolTipErrorMessageMaxHeight = kToolTipMaxWidth / 4;
 
 
 // Helper to widen a view.
@@ -245,9 +246,35 @@ class DownloadShelfContextMenuMac : public DownloadShelfContextMenu {
 }
 
 - (void)updateToolTip {
-  string16 elidedFilename = ui::ElideFilename(
+  string16 tooltip_text = ui::ElideFilename(
       [self download]->GetFileNameToReportUser(), *font_, kToolTipMaxWidth);
-  [progressView_ setToolTip:base::SysUTF16ToNSString(elidedFilename)];
+
+  if ([self download]->GetState() == content::DownloadItem::INTERRUPTED) {
+    content::DownloadInterruptReason reason = [self download]->GetLastReason();
+    DCHECK(reason != 0);
+
+    // Split up the error description string as necessary.
+    std::vector<string16> elidedMessages;
+    ui::ElideRectangleText(
+        DownloadItemModel::InterruptReasonMessage(reason),
+        *font_,
+        kToolTipMaxWidth,
+        kToolTipErrorMessageMaxHeight,
+        ui::IGNORE_LONG_WORDS,
+        &elidedMessages);
+
+    string16 new_line = ASCIIToUTF16("\n");
+    tooltip_text += new_line;
+
+    for (size_t i = 0; i < elidedMessages.size(); ++i) {
+      tooltip_text += elidedMessages[i];
+      tooltip_text += new_line;
+    }
+
+    tooltip_text += bridge_->download_model()->GetProgressText();
+  }
+
+  [progressView_ setToolTip:base::SysUTF16ToNSString(tooltip_text)];
 }
 
 - (void)clearDangerousMode {