[DevTools] Check m_frontendPage in InspectorFrontendHost.

Source/core/inspector/InspectorFrontendHost.cpp

Index: Source/core/inspector/InspectorFrontendHost.cpp
diff --git a/Source/core/inspector/InspectorFrontendHost.cpp b/Source/core/inspector/InspectorFrontendHost.cpp
index db2aefa892760d927062665449bf22e2c9eea3c6..e1afec92d0b206d03d7bb51fca40c9f118deacb4 100644
--- a/Source/core/inspector/InspectorFrontendHost.cpp
+++ b/Source/core/inspector/InspectorFrontendHost.cpp
@@ -146,12 +146,16 @@ void InspectorFrontendHost::disconnectClient()
 
 void InspectorFrontendHost::setZoomFactor(float zoom)
 {
+    if (!m_frontendPage)

[pfeldman, 2014/09/06 10:30:29]

Why does this get called after disconnectClient?

[dgozman, 2014/09/06 10:36:27]

That's a reasonable question. The answer is: I don't know. I cannot repro the
crash, so I'm trying to fix it experimentally. If you have any idea, please
tell.

[pfeldman, 2014/09/06 10:42:29]

Could this be due to microtasks that are dispatching protocol messages?
disconnectClient is called from within willBeDestroyed, so theoretically things
could happen after it.

lgtm 

+        return;
     if (LocalFrame* frame = m_frontendPage->deprecatedLocalMainFrame())
         frame->setPageAndTextZoomFactors(zoom, 1);
 }
 
 float InspectorFrontendHost::zoomFactor()
 {
+    if (!m_frontendPage)
+        return 1;
     if (LocalFrame* frame = m_frontendPage->deprecatedLocalMainFrame())
         return frame->pageZoomFactor();
     return 1;
@@ -159,6 +163,8 @@ float InspectorFrontendHost::zoomFactor()
 
 void InspectorFrontendHost::setInjectedScriptForOrigin(const String& origin, const String& script)
 {
+    if (!m_frontendPage)
+        return;
     m_frontendPage->inspectorController().setInjectedScriptForOrigin(origin, script);
 }