[wip] Introduce SiteInstanceKeepAlive.

content/browser/web_contents/web_contents_view_aura_browsertest.cc

Index: content/browser/web_contents/web_contents_view_aura_browsertest.cc
diff --git a/content/browser/web_contents/web_contents_view_aura_browsertest.cc b/content/browser/web_contents/web_contents_view_aura_browsertest.cc
index 8079c9ce71b9127b38c76bce4a31c3d5dbf78eef..c7f8e44a7d11f149daccf05238f1c2b72e77cf0a 100644
--- a/content/browser/web_contents/web_contents_view_aura_browsertest.cc
+++ b/content/browser/web_contents/web_contents_view_aura_browsertest.cc
@@ -32,6 +32,33 @@
 
 namespace content {
 
+// Keeps track of whether a RenderProcessHost is alive or not.
+class RenderProcessHostTracker : public RenderProcessHostObserver {
+ public:
+  explicit RenderProcessHostTracker(RenderProcessHost* host)
+      : host_(host) {
+    host_->AddObserver(this);
+  }
+
+  virtual ~RenderProcessHostTracker() {
+    if (host_)
+      host_->RemoveObserver(this);
+  }
+
+  bool alive() const { return host_; }
+
+ private:
+  // RenderProcessHostObserver:
+  virtual void RenderProcessHostDestroyed(RenderProcessHost* host) OVERRIDE {
+    CHECK_EQ(host_, host);
+    host_ = NULL;
+  }
+
+  RenderProcessHost* host_;
+
+  DISALLOW_COPY_AND_ASSIGN(RenderProcessHostTracker);
+};
+
 // This class keeps track of the RenderViewHost whose screenshot was captured.
 class ScreenshotTracker : public NavigationEntryScreenshotManager {
  public:
@@ -73,12 +100,22 @@ class ScreenshotTracker : public NavigationEntryScreenshotManager {
     ++waiting_for_screenshots_;
     screenshot_taken_for_ = host;
     NavigationEntryScreenshotManager::TakeScreenshotImpl(host, entry);
+
+    // The screenshot-manager should start observing the lifetime of the
+    // WebContents, to make sure that it can cancel the screenshot requests if
+    // the WebContents is destroyed before the screenshot-capture completes.
+    EXPECT_TRUE(web_contents());
   }
 
   virtual void OnScreenshotSet(NavigationEntryImpl* entry) OVERRIDE {
     --waiting_for_screenshots_;
     screenshot_set_[entry] = true;
     NavigationEntryScreenshotManager::OnScreenshotSet(entry);
+    if (waiting_for_screenshots_ == 0) {
+      // If the screenshot manager is not waiting for any pending screenshot
+      // capture requests, then it shouldn't be observing the WebContents.
+      EXPECT_FALSE(web_contents());
+    }
     if (waiting_for_screenshots_ == 0 && message_loop_runner_.get())
       message_loop_runner_->Quit();
   }
@@ -518,9 +555,16 @@ IN_PROC_BROWSER_TEST_F(WebContentsViewAuraTest,
     params.transition_type = PageTransitionFromInt(navigations[i].transition);
 
     RenderViewHost* old_host = web_contents->GetRenderViewHost();
+    scoped_ptr<RenderProcessHostTracker> process_tracker(
+        new RenderProcessHostTracker(old_host->GetProcess()));
+    EXPECT_TRUE(process_tracker->alive());
+
     web_contents->GetController().LoadURLWithParams(params);
     WaitForLoadStop(web_contents);
     screenshot_manager()->WaitUntilScreenshotIsReady();
+    // The RenderProcessHost should be destroyed, since this is a cross-process
+    // navigation.
+    EXPECT_FALSE(process_tracker->alive());
 
     EXPECT_NE(old_host, web_contents->GetRenderViewHost())
         << navigations[i].url.spec();