Avoid exiting the renderer process if it has a pending render view.

content/browser/renderer_host/render_process_host.h

Index: content/browser/renderer_host/render_process_host.h
diff --git a/content/browser/renderer_host/render_process_host.h b/content/browser/renderer_host/render_process_host.h
index b38402658e297a0061e09cfe23dec2f20da1c73a..5e7d5a796edacac953f66839f81666817928d482 100644
--- a/content/browser/renderer_host/render_process_host.h
+++ b/content/browser/renderer_host/render_process_host.h
@@ -190,6 +190,12 @@ class RenderProcessHost : public IPC::Channel::Sender,
   virtual void WidgetHidden() = 0;
   virtual int VisibleWidgetCount() const = 0;
 
+  // Track the count of pending views that are being swapped back in.  Called
+  // by listeners to register and unregister pending views to prevent the
+  // process from exiting.
+  virtual void AddPendingView() = 0;

[Matt Perry, 2011/05/10 01:14:02]

since this is an interface on the class already, why not just make it
non-virtual and implement it here? The impl doesn't seem to do anything specific
to chrome.

[Charlie Reis, 2011/05/10 01:33:09]

Actually, I'm a little unclear on the difference between RenderProcessHost and
BrowserRenderProcessHost, since both are in content, not chrome.  Right now, the
test version in MockRPH doesn't care about this, so that's the difference
between the two.

John, if you agree that we should move the implementation here, I'm happy to do
that.

[jam, 2011/05/10 04:45:18]

RenderProcessHost was added so that we can have a mock object that implements
the bare interface and use it in tests instead of BrowserRenderProcessHost,
which actually launches processes etc.  I don't have strong opinions on where
the implementation goes.

[Charlie Reis, 2011/05/10 18:42:19]

Ok.  Since there's no harm in having these counters in the tests (and possibly
some value), I've moved the implementation to RenderProcessHost as Matt
suggests.

+  virtual void RemovePendingView() = 0;
+
   // Try to shutdown the associated renderer process as fast as possible.
   // If this renderer has any RenderViews with unload handlers, then this
   // function does nothing.  The current implementation uses TerminateProcess.