[Experiment] purge-and-suspend

third_party/WebKit/Source/core/dom/StyleEngine.cpp

Index: third_party/WebKit/Source/core/dom/StyleEngine.cpp
diff --git a/third_party/WebKit/Source/core/dom/StyleEngine.cpp b/third_party/WebKit/Source/core/dom/StyleEngine.cpp
index 1e36ebbccb8fbe5b045ca04e1592ab466fbd15de..0f9fdf57c551f611e3f277d4e53a64c53a121484 100644
--- a/third_party/WebKit/Source/core/dom/StyleEngine.cpp
+++ b/third_party/WebKit/Source/core/dom/StyleEngine.cpp
@@ -811,6 +811,14 @@ void StyleEngine::keyframesRulesAdded()
     document().timeline().invalidateKeyframeEffects();
 }
 
+void StyleEngine::purgeMemory()
+{
+    clearFontCache();
+    clearResolver();

[esprehn, 2016/08/05 23:00:58]

I think this has some scary side effects, you should double check with rune@,
this also leaves all of the ScopedStyleResolvers. It's going to make us recalc
the entire document I think too.

[tasak, 2016/08/08 04:47:36]

Acknowledged.

I would like to ask one thing. Are you talking about "background to foreground"
full recalc?
As far as I understand, background tabs are suspended and need no layout, no
stylerecalc, and no painting.

+    m_textToSheetCache.clear();
+    m_sheetToTextCache.clear();

[esprehn, 2016/08/05 23:00:58]

This code doesn't really make sense, you're leaving around all of the
ScopedStyleResolvers and the CSSStyleSheet which were created from these
strings. Are you sure this actually saves memory? It shouldn't, the cache here
is just for looking up stuff the rest of the DOM is already using

[tasak, 2016/08/08 04:47:36]

Acknowledged.
I agree that basically these caches' sizes are small and that the impact is very
small.

+}
+
 DEFINE_TRACE(StyleEngine)
 {
     visitor->trace(m_document);