PDF: Yet another stab at getting WriteInto() buffer sizes correct.

pdf/pdfium/pdfium_range.cc

 // Copyright (c) 2010 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.
 
 #include "pdf/pdfium/pdfium_range.h"
 
 #include "base/logging.h"
 #include "base/strings/string_util.h"
 
 namespace chrome_pdf {
@@ skipping 53 matching lines @@
     count *= -1;
     index -= count - 1;
   }
 
   if (count > 0) {
     unsigned short* data =
         reinterpret_cast<unsigned short*>(WriteInto(&rv, count + 1));
     // |written| includes the trailing terminator, so get rid of the trailing
     // NUL character by calling resize().
     int written = FPDFText_GetText(page_->GetTextPage(), index, count, data);
-    if (written < 1)
-      rv.resize(0);
-    else
+    if (written > 0) {
+      DCHECK_EQ(L'\0', rv[written - 1]);
       rv.resize(written - 1);
+    } else {
+      rv.clear();
+    }
   }
 
   return rv;
 }
 
 }  // namespace chrome_pdf