Skip per-script font preferences registration and filling on Android.

chrome/browser/chrome_content_browser_client.cc

 // Copyright (c) 2012 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/chrome_content_browser_client.h"
 
 #include <set>
 #include <utility>
 #include <vector>
 
@@ skipping 461 matching lines @@
       (cert.issuer().common_name == common_name)) {
     return true;
   }
   return false;
 }
 
 // Fills |map| with the per-script font prefs under path |map_name|.
 void FillFontFamilyMap(const PrefService* prefs,
                        const char* map_name,
                        webkit_glue::ScriptFontFamilyMap* map) {
+  // TODO: Get rid of the brute-force scan over possible (font family / script)
+  // combinations - see http://crbug.com/308095.
   for (size_t i = 0; i < prefs::kWebKitScriptsForFontFamilyMapsLength; ++i) {
     const char* script = prefs::kWebKitScriptsForFontFamilyMaps[i];
     std::string pref_name = base::StringPrintf("%s.%s", map_name, script);
     std::string font_family = prefs->GetString(pref_name.c_str());
     if (!font_family.empty())
       (*map)[script] = UTF8ToUTF16(font_family);
   }
 }
 
 #if defined(OS_POSIX) && !defined(OS_MACOSX)
@@ skipping 1591 matching lines @@
 bool ChromeContentBrowserClient::IsFastShutdownPossible() {
   return true;
 }
 
 void ChromeContentBrowserClient::OverrideWebkitPrefs(
     RenderViewHost* rvh, const GURL& url, WebPreferences* web_prefs) {
   Profile* profile = Profile::FromBrowserContext(
       rvh->GetProcess()->GetBrowserContext());
   PrefService* prefs = profile->GetPrefs();
 
+  // Fill per-script font preferences. These are not available on Android and
+  // filling the maps is CPU intensive (http://crbug.com/308033). The ifdef can
+  // be removed after http://crbug.com/308095 is solved.
+#if !defined(OS_ANDROID)

[Yaron, 2013/10/16 16:24:13]

Theres' some related code in chrome/browser/ui/prefs/prefs_tab_helper.cc to
actually register all of these prefs. Happens once on startup but takes over
10ms last I recall. If we're removing the read of these prefs, can we also
remove the registration?

[ppi, 2013/10/16 18:02:36]

Thanks for the pointer! Actually, it looks like the registration of observers
for these preferences was already disabled for Android by Marcus:
https://chromiumcodereview.appspot.com/12529014 .

[Yaron, 2013/10/16 18:08:53]

Ya, I measured after the observers were removed. We still register >1k prefs

   FillFontFamilyMap(prefs, prefs::kWebKitStandardFontFamilyMap,
                     &web_prefs->standard_font_family_map);
   FillFontFamilyMap(prefs, prefs::kWebKitFixedFontFamilyMap,
                     &web_prefs->fixed_font_family_map);
   FillFontFamilyMap(prefs, prefs::kWebKitSerifFontFamilyMap,
                     &web_prefs->serif_font_family_map);
   FillFontFamilyMap(prefs, prefs::kWebKitSansSerifFontFamilyMap,
                     &web_prefs->sans_serif_font_family_map);
   FillFontFamilyMap(prefs, prefs::kWebKitCursiveFontFamilyMap,
                     &web_prefs->cursive_font_family_map);
   FillFontFamilyMap(prefs, prefs::kWebKitFantasyFontFamilyMap,
                     &web_prefs->fantasy_font_family_map);
   FillFontFamilyMap(prefs, prefs::kWebKitPictographFontFamilyMap,
                     &web_prefs->pictograph_font_family_map);
+#endif
 
   web_prefs->default_font_size =
       prefs->GetInteger(prefs::kWebKitDefaultFontSize);
   web_prefs->default_fixed_font_size =
       prefs->GetInteger(prefs::kWebKitDefaultFixedFontSize);
   web_prefs->minimum_font_size =
       prefs->GetInteger(prefs::kWebKitMinimumFontSize);
   web_prefs->minimum_logical_font_size =
       prefs->GetInteger(prefs::kWebKitMinimumLogicalFontSize);
 
@@ skipping 455 matching lines @@
   return IsExtensionOrSharedModuleWhitelisted(url, extension_set,
                                               allowed_file_handle_origins_) ||
          IsHostAllowedByCommandLine(url, extension_set,
                                     switches::kAllowNaClFileHandleAPI);
 #else
   return false;
 #endif
 }
 
 }  // namespace chrome