Use removeFontFace to avoid resetting fontSelector.

Source/web/WebSettingsImpl.cpp

Index: Source/web/WebSettingsImpl.cpp
diff --git a/Source/web/WebSettingsImpl.cpp b/Source/web/WebSettingsImpl.cpp
index 42203da20daf33d1cd3546b393bcf2f3b00ab92c..a74681813816924d68d624a545d57a9713c77a18 100644
--- a/Source/web/WebSettingsImpl.cpp
+++ b/Source/web/WebSettingsImpl.cpp
@@ -67,36 +67,43 @@ WebSettingsImpl::WebSettingsImpl(Settings* settings)
 void WebSettingsImpl::setStandardFontFamily(const WebString& font, UScriptCode script)
 {
     m_settings->genericFontFamilySettings().setStandard(font, script);
+    m_settings->notifyGenericFontFamilyChange();

[dglazkov, 2014/01/29 05:11:50]

These WebSettingImpl functions are never called separately. Look at the
callsites. They are only called when updating web_preferences wholesale. Why do
we need to traverse the frames tree after each call?

[tasak, 2014/01/29 10:13:43]

I would like to confirm what you mean. As far as I investigated,

(1) Each frame has its own document.
(2) Each document has its own StyleEngine and its own CSSFontSelector.
(3) CSSFontSelector has its own GenericFontFamilySettings (different instance
from WebSettingsImpl).

Each page can have multiple frame -- i.e. iframes.

Looking at caller side, chrome just invokes setSansSerifFontFamilyWrapper and
seems not to recreate renderer or reload page?

So ... how can we update all GenericFontFamilySettings without traversing
document?

I think, you are very familiar with GenericFontFamilySettings things. I need
your help.

 }
 
 void WebSettingsImpl::setFixedFontFamily(const WebString& font, UScriptCode script)
 {
     m_settings->genericFontFamilySettings().setFixed(font, script);
+    m_settings->notifyGenericFontFamilyChange();
 }
 
 void WebSettingsImpl::setSerifFontFamily(const WebString& font, UScriptCode script)
 {
     m_settings->genericFontFamilySettings().setSerif(font, script);
+    m_settings->notifyGenericFontFamilyChange();
 }
 
 void WebSettingsImpl::setSansSerifFontFamily(const WebString& font, UScriptCode script)
 {
     m_settings->genericFontFamilySettings().setSansSerif(font, script);
+    m_settings->notifyGenericFontFamilyChange();
 }
 
 void WebSettingsImpl::setCursiveFontFamily(const WebString& font, UScriptCode script)
 {
     m_settings->genericFontFamilySettings().setCursive(font, script);
+    m_settings->notifyGenericFontFamilyChange();
 }
 
 void WebSettingsImpl::setFantasyFontFamily(const WebString& font, UScriptCode script)
 {
     m_settings->genericFontFamilySettings().setFantasy(font, script);
+    m_settings->notifyGenericFontFamilyChange();
 }
 
 void WebSettingsImpl::setPictographFontFamily(const WebString& font, UScriptCode script)
 {
     m_settings->genericFontFamilySettings().setPictograph(font, script);
+    m_settings->notifyGenericFontFamilyChange();
 }
 
 void WebSettingsImpl::setDefaultFontSize(int size)