Fix accessibility issues in custom tab UI

chrome/android/java/strings/android_chrome_strings.grd

Index: chrome/android/java/strings/android_chrome_strings.grd
diff --git a/chrome/android/java/strings/android_chrome_strings.grd b/chrome/android/java/strings/android_chrome_strings.grd
index 1c8a84e93805e3bbc377116343e519d33ca82c97..36137e9fb17bbd46424ff5ea92eec8303eb2fb12 100644
--- a/chrome/android/java/strings/android_chrome_strings.grd
+++ b/chrome/android/java/strings/android_chrome_strings.grd
@@ -2017,6 +2017,9 @@ Just open Chrome on your computer, go to the menu, and select “Sign in to Chro
       <message name="IDS_ACCESSIBILITY_TOOLBAR_BTN_HOME" desc="Content description for the home button.">
         Home
       </message>
+      <message name="IDS_ACCESSIBILITY_TOOLBAR_BTN_CLOSE_WEBPAGE" desc="Content description for the button that closes the webpage.">
+        Close webpage

[newt (away), 2015/06/30 18:44:58]

Should this be "Close tab?" We've already got a string for that BTW.

[Yusuf, 2015/06/30 19:52:30]

Yeah, I think that also makes sense in this context. Let's use "Close Tab" and
avoid adding then new string.

[Ian Wen, 2015/06/30 20:14:38]

Done.

+      </message>
       <message name="IDS_ACCESSIBILITY_TOOLBAR_BTN_CUSTOM" desc="Content description for the custom action button.">
         Custom action button
       </message>