From 9eeec9aa0b983c08abb81fe8b23df66d53830fd3 Mon Sep 17 00:00:00 2001
From: Cheng Zhao <zcbenz@gmail.com>
Date: Fri, 25 Apr 2014 11:22:51 +0800
Subject: [PATCH] Be safe on lifetime of webContents.

---
 atom/browser/api/atom_api_web_contents.cc  | 10 ++++++++++
 atom/browser/api/atom_api_web_contents.h   | 16 ++++++++--------
 atom/browser/api/lib/browser-window.coffee | 18 +++++++++++++-----
 3 files changed, 31 insertions(+), 13 deletions(-)

diff --git a/atom/browser/api/atom_api_web_contents.cc b/atom/browser/api/atom_api_web_contents.cc
index d737914011c1..782e5893f459 100644
--- a/atom/browser/api/atom_api_web_contents.cc
+++ b/atom/browser/api/atom_api_web_contents.cc
@@ -17,11 +17,20 @@ namespace api {
 
 WebContents::WebContents(content::WebContents* web_contents)
     : web_contents_(web_contents) {
+  Observe(web_contents_);
 }
 
 WebContents::~WebContents() {
 }
 
+void WebContents::WebContentsDestroyed(content::WebContents*) {
+  web_contents_ = NULL;
+}
+
+bool WebContents::IsAlive() const {
+  return web_contents_ != NULL;
+}
+
 GURL WebContents::GetURL() const {
   return web_contents_->GetURL();
 }
@@ -62,6 +71,7 @@ void WebContents::ExecuteJavaScript(const string16& code) {
 mate::ObjectTemplateBuilder WebContents::GetObjectTemplateBuilder(
     v8::Isolate* isolate) {
   return mate::ObjectTemplateBuilder(isolate)
+      .SetMethod("isAlive", &WebContents::IsAlive)
       .SetMethod("getUrl", &WebContents::GetURL)
       .SetMethod("getTitle", &WebContents::GetTitle)
       .SetMethod("isLoading", &WebContents::IsLoading)
diff --git a/atom/browser/api/atom_api_web_contents.h b/atom/browser/api/atom_api_web_contents.h
index c1311f9bb938..b15b604903ad 100644
--- a/atom/browser/api/atom_api_web_contents.h
+++ b/atom/browser/api/atom_api_web_contents.h
@@ -6,23 +6,20 @@
 #define ATOM_BROWSER_API_ATOM_API_WEB_CONTENTS_H_
 
 #include "atom/browser/api/event_emitter.h"
+#include "content/public/browser/web_contents_observer.h"
 #include "native_mate/handle.h"
 
-class GURL;
-
-namespace content {
-class WebContents;
-}
-
 namespace atom {
 
 namespace api {
 
-class WebContents : public mate::EventEmitter {
+class WebContents : public mate::EventEmitter,
+                    public content::WebContentsObserver {
  public:
   static mate::Handle<WebContents> Create(v8::Isolate* isolate,
                                           content::WebContents* web_contents);
 
+  bool IsAlive() const;
   GURL GetURL() const;
   string16 GetTitle() const;
   bool IsLoading() const;
@@ -39,7 +36,10 @@ class WebContents : public mate::EventEmitter {
 
   // mate::Wrappable implementations:
   virtual mate::ObjectTemplateBuilder GetObjectTemplateBuilder(
-      v8::Isolate* isolate);
+      v8::Isolate* isolate) OVERRIDE;
+
+  // content::WebContentsObserver implementations:
+  virtual void WebContentsDestroyed(content::WebContents*) OVERRIDE;
 
  private:
   content::WebContents* web_contents_;  // Weak.
diff --git a/atom/browser/api/lib/browser-window.coffee b/atom/browser/api/lib/browser-window.coffee
index 1687604f2f97..04b0a6f4ea33 100644
--- a/atom/browser/api/lib/browser-window.coffee
+++ b/atom/browser/api/lib/browser-window.coffee
@@ -15,15 +15,23 @@ BrowserWindow::_init = ->
     @setMenu menu if menu?
 
   # Define getter for webContents.
-  @__webContents = null
+  webContents = null
   @__defineGetter__ 'webContents', ->
-    @__webContents ?= @getWebContents()
-  @__devToolsWebContents = null
+    webContents ?= @getWebContents()
+    # Return null if webContents is destroyed.
+    webContents = null unless webContents?.isAlive()
+    webContents
+
+  # And devToolsWebContents.
+  devToolsWebContents = null
   @__defineGetter__ 'devToolsWebContents', ->
     if @isDevToolsOpened()
-      @__devToolsWebContents ?= @getDevToolsWebContents()
+      # Get the new devToolsWebContents if previous one has been destroyed, it
+      # could happen when the devtools has been closed and then reopened.
+      devToolsWebContents = null unless devToolsWebContents?.isAlive()
+      devToolsWebContents ?= @getDevToolsWebContents()
     else
-      @__devToolsWebContents = null
+      devToolsWebContents = null
 
   # Remember the window.
   id = BrowserWindow.windows.add this