IWYU: include algorithm to use std::lower_bound in ui/gfx/font.cc

Fix GCC build because of missing include:
../../ui/gfx/font.cc: In function ‘gfx::Font::Weight gfx::FontWeightFromInt(int)’:
../../ui/gfx/font.cc:114:8: error: no matching function for call to ‘lower_bound(const gfx::Font::Weight*, const gfx::Font::Weight*, int&, gfx::FontWeightFromInt(int)::<lambda(const gfx::Font::Weight&, const int&)>)’
       });
        ^
In file included from /usr/include/c++/8/bits/char_traits.h:39,
                 from /usr/include/c++/8/string:40,
                 from ../../ui/gfx/font.h:8,
                 from ../../ui/gfx/font.cc:5:
/usr/include/c++/8/bits/stl_algobase.h:984:5: note: candidate: ‘template<class _ForwardIterator, class _Tp> _ForwardIterator std::lower_bound(_ForwardIterator, _ForwardIterator, const _Tp&)’
     lower_bound(_ForwardIterator __first, _ForwardIterator __last,
     ^~~~~~~~~~~
/usr/include/c++/8/bits/stl_algobase.h:984:5: note:   template argument deduction/substitution failed:
../../ui/gfx/font.cc:114:8: note:   candidate expects 3 arguments, 4 provided
       });
        ^

Bug: 819294
Change-Id: Ic59dcf3a06bdd54d1d426c08a61624873a0ff30c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1879909
Commit-Queue: Alexei Svitkine <asvitkine@chromium.org>
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Cr-Commit-Position: refs/heads/master@{#709472}

ui/gfx/font.cc

@@ -4,6 +4,8 @@
 
 #include "ui/gfx/font.h"
 
+#include <algorithm>
+
 #include "base/strings/utf_string_conversions.h"
 #include "build/build_config.h"
 #include "ui/gfx/platform_font.h"