Added strings for notification when user presses backspace.

chrome/app/generated_resources.grd

Index: chrome/app/generated_resources.grd
diff --git a/chrome/app/generated_resources.grd b/chrome/app/generated_resources.grd
index cdaf2d756f124a977e41dbb68ec03639e72a4bff..b5b4be692f75f82025c51b97fa92a0d7d9d78c2a 100644
--- a/chrome/app/generated_resources.grd
+++ b/chrome/app/generated_resources.grd
@@ -12663,6 +12663,14 @@ Some features may be unavailable.  Please check that the profile exists and you
         Deny
       </message>
 
+      <!-- Backspace shortcut notification strings -->
+      <message name="IDS_PRESS_ALT_LEFT_TO_GO_BACK" desc="Text displayed in the bubble to explain the keyboard shortcut to go back to the previous web page in history. The accelerators are names of keyboard keys. Please surround the names of the keys (e.g. 'Alt' and '←') in pipe characters so they can be rendered correctly.">
+        Press |<ph name="ACCELERATOR1">$1<ex>Alt</ex></ph>|+|<ph name="ACCELERATOR2">$2<ex>←</ex></ph>| to go back
+      </message>
+      <message name="IDS_PRESS_ALT_RIGHT_TO_GO_FORWARD" desc="Text displayed in the bubble to explain the keyboard shortcut to go forward to the next web page in history. The accelerators are names of keyboard keys. Please surround the names of the keys (e.g. 'Alt' and '→') in pipe characters so they can be rendered correctly.">
+        Press |<ph name="ACCELERATOR1">$1<ex>Alt</ex></ph>|+|<ph name="ACCELERATOR2">$2<ex>→</ex></ph>| to go forward
+      </message>
+
       <!-- Register Protocol Handler Strings -->
       <message name="IDS_REGISTER_PROTOCOL_HANDLER_MAILTO_NAME" desc="A more user friendly way of describing mailto: links.">
         email