Add base:: namespace to straggling string16s left in chrome/browser/ui.

chrome/browser/ui/cocoa/find_bar/find_bar_cocoa_controller.mm

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/auto_reset.h"
 #include "base/mac/bundle_locations.h"
 #include "base/mac/mac_util.h"
 #include "base/strings/sys_string_conversions.h"
@@ skipping 194 matching lines @@
     [[FindPasteboard sharedInstance] setFindText:findText];
   }
 
   if ([findText length] > 0) {
     findTabHelper->
         StartFinding(base::SysNSStringToUTF16(findText), true, false);
   } else {
     // The textbox is empty so we reset.
     findTabHelper->StopFinding(FindBarController::kClearSelectionOnPage);
     [self updateUIForFindResult:findTabHelper->find_result()
-                       withText:string16()];
+                       withText:base::string16()];
   }
 }
 
 // NSControl delegate method
 - (BOOL)control:(NSControl*)control
     textView:(NSTextView*)textView
     doCommandBySelector:(SEL)command {
   if (command == @selector(insertNewline:)) {
     // Pressing Return
     NSEvent* event = [NSApp currentEvent];
@@ skipping 150 matching lines @@
     BOOL buttonsEnabled = [[findText_ stringValue] length] > 0 ? YES : NO;
     [previousButton_ setEnabled:buttonsEnabled];
     [nextButton_ setEnabled:buttonsEnabled];
     [[findText_ findBarTextFieldCell] clearResults];
   }
 }
 
 - (void)clearResults:(const FindNotificationDetails&)results {
   // Just call updateUIForFindResult, which will take care of clearing
   // the search text and the results label.
-  [self updateUIForFindResult:results withText:string16()];
+  [self updateUIForFindResult:results withText:base::string16()];
 }
 
 - (void)updateUIForFindResult:(const FindNotificationDetails&)result
                      withText:(const base::string16&)findText {
   // If we don't have any results and something was passed in, then
   // that means someone pressed Cmd-G while the Find box was
   // closed. In that case we need to repopulate the Find box with what
   // was passed in.
   if ([[findText_ stringValue] length] == 0 && !findText.empty()) {
     [findText_ setStringValue:base::SysUTF16ToNSString(findText)];
@@ skipping 224 matching lines @@
 }
 
 - (BrowserWindowController*)browserWindowController {
   if (!browser_)
     return nil;
   return [BrowserWindowController
       browserWindowControllerForWindow:browser_->window()->GetNativeWindow()];
 }
 
 @end