Improvements to tab title prefix eliding as per email discussions.

chrome/browser/ui/views/tabs/base_tab.cc

Index: chrome/browser/ui/views/tabs/base_tab.cc
===================================================================
--- chrome/browser/ui/views/tabs/base_tab.cc	(revision 79877)
+++ chrome/browser/ui/views/tabs/base_tab.cc	(working copy)
@@ -479,11 +479,15 @@
     Browser::FormatTitleForDisplay(&title);
     // If we'll need to truncate, check if we should also truncate
     // a common prefix, but only if there is enough room for it.
-    // We arbitrarily choose to request enough room for 10 average chars.
-    if (data().common_prefix_length > 0 &&
-        font_->GetExpectedTextWidth(10) < title_bounds.width() &&
+    // We arbitrarily choose to request enough room for 6 average chars.
+    // Also, we want to show the last 4 common chars, so we only do it if
+    // the common prefix is at least 7 characters long, otherwise, we would be
+    // replacing 3 or less characters with a 3 dot ellipsis... not worth it.
+    if (data().common_prefix_length > 7 &&
+        font_->GetExpectedTextWidth(6) < title_bounds.width() &&
         font_->GetStringWidth(title) > title_bounds.width()) {
-      title.replace(0, data().common_prefix_length, UTF8ToUTF16(ui::kEllipsis));
+      title.replace(0, data().common_prefix_length - 4,
+                    UTF8ToUTF16(ui::kEllipsis));
     }
   }
   canvas->DrawStringInt(title, *font_, title_color,