Remove string with no content from generated_resources.grd.

This removes IDS_EXTENSION_PROMPT_WARNING_USB_DEVICE_LIST_ITEM, which
contained no content besides a placeholder tag. This string wasn't
translatable, but showed up as "untranslated" string in internal tools
because of its strange state.

Review URL: https://codereview.chromium.org/1438293003

Cr-Commit-Position: refs/heads/master@{#359586}

chrome/app/generated_resources.grd

@@ -4100,9 +4100,6 @@ Even if you have downloaded files from this website before, the website might ha
         <message name="IDS_EXTENSION_PROMPT_WARNING_USB_DEVICE_LIST" desc="Permission string for access to a list of USB devices.">
           Access any of these USB devices
         </message>
-        <message name="IDS_EXTENSION_PROMPT_WARNING_USB_DEVICE_LIST_ITEM" desc="Line item for a USB device listed under IDS_EXTENSION_PROMPT_WARNING_USB_DEVICE_LIST.">
-          <ph name="DEVICE_NAME_AND_VENDOR">$1<ex>SoundKnob from Griffin Technology</ex></ph>
-        </message>
         <message name="IDS_EXTENSION_PROMPT_WARNING_USB_DEVICE_LIST_ITEM_UNKNOWN_PRODUCT" desc="Line item for a USB device listed under IDS_EXTENSION_PROMPT_WARNING_USB_DEVICE_LIST that has an unknown product ID.">
           unknown devices from <ph name="VENDOR_NAME">$1<ex>Griffin Technology</ex></ph>
         </message>

chrome/common/extensions/permissions/chrome_permission_message_rules.cc

@@ -217,14 +217,9 @@ class USBDevicesFormatter : public ChromePermissionMessageFormatter {
       const PermissionIDSet& permissions) const {
     DCHECK(permissions.size() > 1);
     // Put all the individual items into submessages.
-    std::vector<base::string16> submessages;
-    std::vector<base::string16> devices =
+    std::vector<base::string16> submessages =
         permissions.GetAllPermissionsWithID(APIPermission::kUsbDevice)
             .GetAllPermissionParameters();
-    for (const base::string16& device : devices) {
-      submessages.push_back(l10n_util::GetStringFUTF16(
-          IDS_EXTENSION_PROMPT_WARNING_USB_DEVICE_LIST_ITEM, device));
-    }
     std::vector<base::string16> vendors =
         permissions.GetAllPermissionsWithID(
                        APIPermission::kUsbDeviceUnknownProduct)