Fix for InspectorOverlay violating document lifecycle expectations

Source/core/inspector/InspectorOverlay.cpp

Index: Source/core/inspector/InspectorOverlay.cpp
diff --git a/Source/core/inspector/InspectorOverlay.cpp b/Source/core/inspector/InspectorOverlay.cpp
index 32016f3b1f56f21c13adb4c2c7a4e42263f4ecd1..d5ab4f36bd97dd7b02b247660d3a58468389f63f 100644
--- a/Source/core/inspector/InspectorOverlay.cpp
+++ b/Source/core/inspector/InspectorOverlay.cpp
@@ -345,6 +345,7 @@ InspectorOverlay::InspectorOverlay(Page* page, InspectorClient* client)
     , m_omitTooltip(false)
     , m_timer(this, &InspectorOverlay::onTimer)
     , m_activeProfilerCount(0)
+    , m_updating(false)
 {
 }
 
@@ -365,6 +366,11 @@ void InspectorOverlay::paint(GraphicsContext& context)
 
 void InspectorOverlay::invalidate()
 {
+    // Don't invalidate during an update, because that will lead to Document::scheduleRenderTreeUpdate
+    // being called within Document::updateRenderTree which violates document lifecycle expectations.
+    if (m_updating)
+        return;
+
     m_client->highlight();

[dgozman, 2014/12/06 12:34:18]

This call usually just adds/removes a GraphicsLayer, which should not cause any
layouts or style invalidations.

Perhaps, the problem is in layout call here:
https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit...

This only happens during page load when inspector overlay is triggered before
layout (e.g. breakpoint at the start). Should we just check that webview does
not already doing layout?

 }
 
@@ -477,6 +483,8 @@ bool InspectorOverlay::isEmpty()
 
 void InspectorOverlay::update()
 {
+    TemporaryChange<bool> scoped(m_updating, true);
+
     if (isEmpty()) {
         m_client->hideHighlight();
         return;