Fix issues related to request and context object lifespan (issue #1037, issue #1044).

- Simplify and document the relationship between the various context object types. See browser_context.h for a description of the new relationships.
- cefclient: Add `request-context-per-browser` command-line flag for testing multiple CefRequestContext instances.
- cefclient: Add a CefURLRequest example.

git-svn-id: https://chromiumembedded.googlecode.com/svn/trunk@2032 5089003a-bbd8-11dd-ad1f-f1f9622dbc98

tests/cefclient/browser/root_window.h

@@ -25,6 +25,11 @@ class RootWindow :
   // of this class will be called on the main thread.
   class Delegate {
    public:
+    // Called to retrieve the CefRequestContext for browser. Only called for
+    // non-popup browsers. May return NULL.
+    virtual CefRefPtr<CefRequestContext> GetRequestContext(
+        RootWindow* root_window) = 0;
+
     // Called to execute a test. See resource.h for |test_id| values.
     virtual void OnTest(RootWindow* root_window, int test_id) = 0;