Fixes for re-enabling more MSVC level 4 warnings: ui/ edition

ui/gfx/render_text_harfbuzz.cc

 // Copyright 2014 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 "ui/gfx/render_text_harfbuzz.h"
 
 #include <map>
 
 #include "base/debug/leak_annotations.h"
 #include "base/i18n/bidi_line_iterator.h"
@@ skipping 387 matching lines @@
 }  // namespace
 
 namespace internal {
 
 TextRunHarfBuzz::TextRunHarfBuzz()
     : width(0),
       preceding_run_widths(0),
       is_rtl(false),
       level(0),
       script(USCRIPT_INVALID_CODE),
-      glyph_count(-1),
+      glyph_count(static_cast<size_t>(-1)),
       font_size(0),
       font_style(0),
       strike(false),
       diagonal_strike(false),
       underline(false) {}
 
 TextRunHarfBuzz::~TextRunHarfBuzz() {}
 
 size_t TextRunHarfBuzz::CharToGlyph(size_t pos) const {
   DCHECK(range.start() <= pos && pos < range.end());
@@ skipping 573 matching lines @@
     run->positions[i].set(run->width + x_offset, -y_offset);
     run->width +=
         SkScalarRoundToInt(SkFixedToScalar(hb_positions[i].x_advance));
   }
 
   hb_buffer_destroy(buffer);
   hb_font_destroy(harfbuzz_font);
 }
 
 }  // namespace gfx