views: Add protected virtual destructor to TabbedPaneListener.
views: Add protected virtual destructor to TabbedPaneListener.

The use of a protected virtual destructor is to prevent the destruction of a
derived object via a base-class pointer.

That's it, TabbedPaneListenere should only be deleted through derived class.

Example:

class FooListener {
 public:
  ...

 protected:
  virtual ~FooListener() {}
};

class Foo : public FooListener {
};

FooListener* listener = new Foo;
delete listener;  // It should prevent this situation!

R=sky@chromium.org

Review URL: http://codereview.chromium.org/8028030

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@102916 0039d316-1c4b-4281-b951-d872f2087c98

ropik/chromium,ropik/chromium,adobe/chromium,ropik/chromium,gavinp/chromium,adobe/chromium,yitian134/chromium,gavinp/chromium,adobe/chromium,gavinp/chromium,adobe/chromium,gavinp/chromium,yitian134/chromium,yitian134/chromium,ropik/chromium,ropik/chromium,gavinp/chromium,adobe/chromium,adobe/chromium,gavinp/chromium,gavinp/chromium,adobe/chromium,yitian134/chromium,yitian134/chromium,yitian134/chromium,ropik/chromium,adobe/chromium,yitian134/chromium,yitian134/chromium,yitian134/chromium,adobe/chromium,adobe/chromium,gavinp/chromium,ropik/chromium,yitian134/chromium,adobe/chromium,ropik/chromium,gavinp/chromium,gavinp/chromium,ropik/chromium