Should check whether document.settings() is available or not when updating GenericFontFamilySetting…

Source/core/dom/StyleEngine.cpp

Index: Source/core/dom/StyleEngine.cpp
diff --git a/Source/core/dom/StyleEngine.cpp b/Source/core/dom/StyleEngine.cpp
index cf956cc58d465fd514eff2b9c7fb91a6e8f07a45..f67e605c19bbb5de5b2ddf4f8cb7b6c371382020 100644
--- a/Source/core/dom/StyleEngine.cpp
+++ b/Source/core/dom/StyleEngine.cpp
@@ -525,6 +525,15 @@ void StyleEngine::clearFontCache()
 
 void StyleEngine::updateGenericFontFamilySettings()
 {
+    // FIXME: in-active documents should not be in any frame tree.

[abarth-chromium, 2014/06/06 17:02:02]

That's not accurate.  Documents become inactive and then they leave the frame
tree.  During shutdown, there is a period of time after they become inactive
before they are removed from the frame tree.

[tasak, 2014/06/09 04:41:26]

Thank you. I updated the comment.

+    // After confirming that this condition is always true,
+    // remove the fllowing ASSERT.

[abarth-chromium, 2014/06/06 17:02:02]

fllowing -> following

[tasak, 2014/06/09 04:41:26]

Done.

+    ASSERT(document().isActive());
+
+    // Since document::settings() can return null, need to check whether
+    // document has settings or not. crbug.com/376525

[abarth-chromium, 2014/06/06 17:02:02]

Please remove this comment. If settings() couldn't be null, then there would be
no need for line 535. Instead of a comment referring to a bug, we should have an
automated test that triggers the condition.

[tasak, 2014/06/09 04:41:26]

I agree that we should have automated test.

However, I cannot reproduce this issue. So I have no idea about how to trigger
the condition.

+    if (!document().settings())
+        return;

[abarth-chromium, 2014/06/06 17:05:29]

Why are you checking the Settings object here? I don't see any references to the
Settings object in this function.  Typically we null-check the Settings object
immediately before accessing it.

[tasak, 2014/06/09 04:41:25]

I see. I moved the check to CSSFontSelector::updateGenericFontFamilySettings.

     if (!m_fontSelector)
         return;