Replace BrowserProces::AddRefModule/RemoveModule by ScopedKeepAlive

chrome/browser/browser_process.h

Index: chrome/browser/browser_process.h
diff --git a/chrome/browser/browser_process.h b/chrome/browser/browser_process.h
index 176558d8628d56f9835780070813bf9c5c02464d..a72190c6d5404d701fe9ebb5e9a59346fa2aae42 100644
--- a/chrome/browser/browser_process.h
+++ b/chrome/browser/browser_process.h
@@ -186,8 +186,9 @@ class BrowserProcess {
                                                  uint16_t port) = 0;
   virtual void CreateDevToolsAutoOpener() = 0;
 
-  virtual unsigned int AddRefModule() = 0;
-  virtual unsigned int ReleaseModule() = 0;
+  // Called by KeepAliveRegistry to control Chrome's lifetime.
+  virtual void Pin() = 0;

[sky, 2016/03/16 16:04:32]

I don't like having these public as then anyone can call them, which we don't
want. How about having KeepAliveRegistry talk to a delegate that browserprocess
implements? That way you can make these protected.

[dgn, 2016/03/16 22:28:35]

Good idea, it also allows to get rid of a lot of code that disabled shutdown for
unit tests, by just not registering the listener in TestingBrowserProcess, which
is nice.

I used KeepAliveStateObserver to do it. WDYT? 

+  virtual void Unpin() = 0;
 
   virtual bool IsShuttingDown() = 0;