Navigation transitions (web to native app): Revert exit transition (Blink side)

Source/core/css/CSSStyleSheet.cpp

Index: Source/core/css/CSSStyleSheet.cpp
diff --git a/Source/core/css/CSSStyleSheet.cpp b/Source/core/css/CSSStyleSheet.cpp
index 705d3283da8707459b4002a670ea53176e068975..ec71fd782dceaeca784ba7d1d4f1c2b591212062 100644
--- a/Source/core/css/CSSStyleSheet.cpp
+++ b/Source/core/css/CSSStyleSheet.cpp
@@ -37,6 +37,7 @@
 #include "core/dom/ExceptionCode.h"
 #include "core/dom/Node.h"
 #include "core/frame/UseCounter.h"
+#include "core/html/HTMLLinkElement.h"
 #include "core/html/HTMLStyleElement.h"
 #include "core/inspector/InspectorInstrumentation.h"
 #include "core/svg/SVGStyleElement.h"
@@ -223,7 +224,17 @@ void CSSStyleSheet::setDisabled(bool disabled)
         return;
     m_isDisabled = disabled;
 
-    didMutate();
+    bool isTransitionExitingStylesheet = false;
+    if (isHTMLLinkElement(*m_ownerNode)) {
+        HTMLLinkElement& linkElement = toHTMLLinkElement(*m_ownerNode);
+        isTransitionExitingStylesheet =
+            linkElement.relAttribute().isTransitionExitingStylesheet();
+    }
+
+    if (isTransitionExitingStylesheet)
+        didMutate(EntireStyleSheetUpdate);

[esprehn, 2014/10/15 18:01:26]

Transition sheets shouldn't be special, CSSStyleSheet should not know anything
about this part of the system. This is the wrong layering.

[Zhen Wang, 2014/10/15 19:50:58]

The default will lead to FullStyleUpdate. We need AnalyzedStyleUpdate. 

See the demo video in the CL description. I navigate from the page to a native
app and then press the back button to come back. If I don't treat transition
stylesheets specially here, the user interaction will not function properly
after coming back (cannot click to navigate any more.)

This is related to the comments in HTMLLinkElement.cpp.

[esprehn, 2014/10/15 20:19:07]

This is not correct, I don't know what you're talking about. AnalyzedStyleUpdate
is just an attempt to do an optimization over the FullStyleUpdate. It's a subset
of the amount of work done, but they should have exactly the same end result. We
should be able to switch all AnalyzedStyleUpdate over to FullStyleUpdate and
have an engine that functions the same.

[Zhen Wang, 2014/10/15 23:04:41]

I agree that this is a strange behavior. I am not familiar with the style code.
I have tested the effect with both default value and AnalyzedStyleUpdate. Using
AnalyzedStyleUpdate solved the problem. My guess is that there is some side
effect.

I think it may be easier to show you the effect in person. Are you in office
tomorrow?

[Zhen Wang, 2014/12/03 17:54:29]

This is fixed by resetIsTransitionDocument now. 

+    else
+        didMutate();
 }
 
 void CSSStyleSheet::setMediaQueries(PassRefPtrWillBeRawPtr<MediaQuerySet> mediaQueries)