Makes the default ctor of gfx::FontList copy the pre-calculated metrics.

ui/gfx/font_list.cc

Index: ui/gfx/font_list.cc
diff --git a/ui/gfx/font_list.cc b/ui/gfx/font_list.cc
index e977882bed90ea4d96a30e8e4859e4423839ca8e..ff1daf780d5763c08e11d2a4a85400705b03a402 100644
--- a/ui/gfx/font_list.cc
+++ b/ui/gfx/font_list.cc
@@ -6,7 +6,6 @@
 
 #include <algorithm>
 
-#include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_split.h"
@@ -14,9 +13,10 @@
 
 namespace {
 
-// Font description of the default font set.
-base::LazyInstance<std::string>::Leaky g_default_font_description =
-    LAZY_INSTANCE_INITIALIZER;
+// The default instance of gfx::FontList, whose metrics are pre-calculated.
+// The default ctor of gfx::FontList copies the metrics so it won't need to
+// scan the whole font list to calculate the metrics.
+gfx::FontList* g_default_font_list = NULL;
 
 // Parses font description into |font_names|, |font_style| and |font_size|.
 void ParseFontDescriptionString(const std::string& font_description_string,
@@ -80,14 +80,14 @@ FontList::FontList()
       common_baseline_(-1),
       font_style_(-1),
       font_size_(-1) {
-  // SetDefaultFontDescription() must be called and the default font description
-  // must be set earlier than any call of the default constructor.
-  DCHECK(!(g_default_font_description == NULL))  // != is not overloaded.
+  // SetDefaultFontDescription() must be called earlier than any call of the
+  // default constructor.
+  DCHECK(g_default_font_list)
       << "SetDefaultFontDescription has not been called.";
 
-  font_description_string_ = g_default_font_description.Get();
-  if (font_description_string_.empty())
-    fonts_.push_back(Font());
+  // Copy the default font list specification as well as the pre-calculated

[msw, 2014/01/07 17:51:38]

nit: s/as well as the/and its/

[Yuki, 2014/01/08 06:32:19]

Done.

+  // metrics.
+  *this = *g_default_font_list;
 }
 
 FontList::FontList(const std::string& font_description_string)
@@ -144,12 +144,14 @@ FontList::~FontList() {
 
 // static
 void FontList::SetDefaultFontDescription(const std::string& font_description) {
-  // The description string must end with "px" for size in pixel, or must be
-  // the empty string, which specifies to use a single default font.
-  DCHECK(font_description.empty() ||
-         EndsWith(font_description, "px", true));
-
-  g_default_font_description.Get() = font_description;
+  static FontList default_font_list((Font()));

[msw, 2014/01/07 17:51:38]

nit: remove extra parens around Font().

[Yuki, 2014/01/08 06:32:19]

This is necessary.  Without them, it's ambiguous if it's a function declaration
or a variable declaration.  default_font_list may look like a function which
returns a FontList and takes a Font.

+  g_default_font_list = &default_font_list;
+
+  default_font_list = font_description.empty() ?

[msw, 2014/01/07 17:51:38]

nit: make this if (!font_description.empty()) default_font_list =
FontList(font_description);

[Yuki, 2014/01/08 06:32:19]

When ui::ResourceBundle reloads the resources including fonts,
SetDefaultFontDescription() was called twice and more.  So we have to reset
|default_font_list| according to the given |font_description|.  If
font_description.empty(), we should reset |default_font_list| with a font list
which has a default Font.

+      FontList(Font()) : FontList(font_description);
+  // Pre-calculate the metrics.
+  default_font_list.CacheCommonFontHeightAndBaseline();
+  default_font_list.CacheFontStyleAndSize();
 }
 
 FontList FontList::DeriveFontList(int font_style) const {