Add a cache for FillFontFamilyMap.

chrome/browser/font_family_cache_unittest.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 "chrome/browser/font_family_cache.h"
+
+#include "base/prefs/pref_registry_simple.h"
+#include "base/prefs/testing_pref_service.h"
+#include "base/strings/utf_string_conversions.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace {
+
+class TestingFontFamilyCache : public chrome::FontFamilyCache {
+ public:
+  explicit TestingFontFamilyCache(PrefService* prefs)
+      : chrome::FontFamilyCache(prefs), fetch_font_count_(0) {}
+  virtual ~TestingFontFamilyCache() {}
+  virtual base::string16 FetchFont(const char* script,
+                                   const char* map_name) OVERRIDE {
+    ++fetch_font_count_;
+    return chrome::FontFamilyCache::FetchFont(script, map_name);
+  }
+
+  int fetch_font_count_;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(TestingFontFamilyCache);
+};
+
+}  // namespace
+
+// Tests that the cache is correctly set and cleared.
+TEST(FontFamilyCacheTest, Caching) {
+  TestingPrefServiceSimple prefs;
+  TestingFontFamilyCache cache(&prefs);
+
+  std::string font1("font 1");
+  std::string font2("font 2");
+  std::string map_name("webkit.webprefs.fonts.pictograph");
+  std::string script("Syrn");
+  std::string pref_name(map_name + '.' + script);
+  std::string pref_name2(map_name + '.' + "adsf");
+
+  // Registers 2 preferences, and sets the first one.
+  prefs.registry()->RegisterStringPref(pref_name.c_str(), std::string());
+  prefs.registry()->RegisterStringPref(pref_name2.c_str(), std::string());
+  prefs.SetString(pref_name.c_str(), font1.c_str());
+
+  // Check that the right preference is returned.
+  std::string result = base::UTF16ToUTF8(
+      cache.FetchAndCacheFont(script.c_str(), map_name.c_str()));
+  EXPECT_EQ(result, font1);

[Lei Zhang, 2014/08/05 19:26:49]

nit: EXPECT_EQ(expected, actual)

Otherwise if this fails, the message gtest prints looks funny.

[erikchen, 2014/08/05 20:49:23]

Done.

+  EXPECT_EQ(cache.fetch_font_count_, 1);
+
+  // Check that the second access uses the cache.
+  result = base::UTF16ToUTF8(
+      cache.FetchAndCacheFont(script.c_str(), map_name.c_str()));
+  EXPECT_EQ(result, font1);
+  EXPECT_EQ(cache.fetch_font_count_, 1);
+
+  // Changing another preference should have no effect.
+  prefs.SetString(pref_name2.c_str(), "katy perry");
+  result = base::UTF16ToUTF8(
+      cache.FetchAndCacheFont(script.c_str(), map_name.c_str()));
+  EXPECT_EQ(result, font1);
+  EXPECT_EQ(cache.fetch_font_count_, 1);
+
+  // Changing the preferences invalidates the cache.
+  prefs.SetString(pref_name.c_str(), font2.c_str());
+  result = base::UTF16ToUTF8(
+      cache.FetchAndCacheFont(script.c_str(), map_name.c_str()));
+  EXPECT_EQ(result, font2);
+  EXPECT_EQ(cache.fetch_font_count_, 2);
+}