athena: Add the concept of Activity and related managers.

athena/main/placeholder_content.cc

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "athena/main/placeholder_content.h"
+
+#include "athena/activity/public/activity_manager.h"
+#include "athena/main/web_activity.h"
+#include "content/public/browser/web_contents.h"
+
+void CreateTestPages(content::BrowserContext* browser_context) {
+  const char* kTestURLs[] = {
+      "http://cyan.bikeshed.com", "https://www.google.com",
+  };
+  for (size_t i = 0; i < arraysize(kTestURLs); ++i) {
+    content::WebContents::CreateParams params(browser_context);
+    content::WebContents* contents = content::WebContents::Create(params);
+    contents->GetController().LoadURL(GURL(kTestURLs[i]),
+                                      content::Referrer(),
+                                      content::PAGE_TRANSITION_TYPED,
+                                      std::string());
+    athena::ActivityManager::Get()->AddActivity(new WebActivity(contents));
+    contents->Focus();
+  }
+}