[Cleanup] Factor out common code.

chrome/browser/ui/chrome_pages.cc

 // Copyright (c) 2012 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 "chrome/browser/ui/chrome_pages.h"
 
 #include <stddef.h>
 
 #include "base/command_line.h"
 #include "base/logging.h"
@@ skipping 116 matching lines @@
 #endif
 }
 
 std::string GenerateContentSettingsExceptionsSubPage(ContentSettingsType type) {
   return kContentSettingsExceptionsSubPage + std::string(kHashMark) +
          options::ContentSettingsHandler::ContentSettingsTypeToGroupName(type);
 }
 
 }  // namespace
 
+bool IsInternalPage(const GURL& url) {
+  // TODO(groby): Figure out if TabManager/session restore rely on this
+  // being a shortened list, or if all WebUI pages qualify.
+
+  // There are many chrome:// UI URLs, but only look for the ones that users
+  // are likely to have open. Most of the benefit is from the NTP URL.
+  const char* const kReloadableUrlPrefixes[] = {
+      chrome::kChromeUIDownloadsURL, chrome::kChromeUIHistoryURL,
+      chrome::kChromeUINewTabURL, chrome::kChromeUISettingsURL,
+  };
+  // Prefix-match against the table above. Use strncmp to avoid allocating
+  // memory to convert the URL prefix constants into std::strings.

[Dan Beam, 2016/06/02 02:20:38]

why do we have to avoid this?  because it's called from memory-sensitive code?

+  for (size_t i = 0; i < arraysize(kReloadableUrlPrefixes); ++i) {
+    if (!strncmp(url.spec().c_str(), kReloadableUrlPrefixes[i],
+                 strlen(kReloadableUrlPrefixes[i])))
+      return true;

[Dan Beam, 2016/06/02 02:20:38]

culies?

[Dan Beam, 2016/06/02 02:20:49]

curlies*

+  }

[Dan Beam, 2016/06/02 02:20:38]

i don't really think this for loop of 4 entries is buying us much

+  return false;
+}
+
 void ShowBookmarkManager(Browser* browser) {
   content::RecordAction(UserMetricsAction("ShowBookmarkManager"));
   content::RecordAction(UserMetricsAction("ShowBookmarks"));
   ShowSingletonTabOverwritingNTP(
       browser,
       GetSingletonTabNavigateParams(browser, GURL(kChromeUIBookmarksURL)));
 }
 
 void ShowBookmarkManagerForNode(Browser* browser, int64_t node_id) {
   OpenBookmarkManagerWithHash(browser, std::string(), node_id);
@@ skipping 246 matching lines @@
       SigninManagerFactory::GetForProfile(original_profile);
   DCHECK(manager->IsSigninAllowed());
   if (manager->IsAuthenticated())
     ShowSettings(browser);
   else
     ShowBrowserSignin(browser, access_point);
 }
 #endif
 
 }  // namespace chrome