chrome/browser/ui/tab_helpers.h

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CHROME_BROWSER_UI_TAB_HELPERS_H_
   6 #define CHROME_BROWSER_UI_TAB_HELPERS_H_
   7
   8 namespace content {
   9 class WebContents;
  10 }
  11
  12 namespace chrome {
  13 class BrowserTabStripModelDelegate;
  14
  15 namespace android {
  16 class ChromeWebContentsDelegateAndroid;
  17 }
  18 }
  19
  20 namespace prerender {
  21 class PrerenderContents;
  22 }
  23
  24 // A "tab contents" is a WebContents that is used as a tab in a browser window
  25 // (or the equivalent on Android). The TabHelpers class allows specific classes
  26 // to attach the set of tab helpers that is used for tab contents.
  27 //
  28 // https://chromium.googlesource.com/chromium/src/+/master/docs/tab_helpers.md
  29 //
  30 // TODO(avi): This list is rather large, and for most callers it's due to the
  31 // fact that they need tab helpers attached early to deal with arbitrary
  32 // content loaded into a WebContents that will later be added to the tabstrip.
  33 // Is there a better way to handle this? (Ideally, this list would contain
  34 // only Browser and BrowserTabStripModelDelegate.)
  35 class TabHelpers {
  36  private:
  37   // Browser and its TabStripModelDelegate have intimate control of tabs.
  38   // TabAndroid is the equivalent on Android.
  39   friend class Browser;
  40   friend class chrome::BrowserTabStripModelDelegate;
  41
  42   // These are the Android equivalents of the two classes above.
  43   friend class TabAndroid;
  44   friend class chrome::android::ChromeWebContentsDelegateAndroid;
  45
  46   // chrome::Navigate creates WebContents that are destined for the tab strip,
  47   // and that might have WebUI that immediately calls back into random tab
  48   // helpers.
  49   friend class BrowserNavigatorWebContentsAdoption;
  50
  51   // Prerendering loads pages that have arbitrary external content; it needs
  52   // the full set of tab helpers to deal with it.
  53   friend class prerender::PrerenderContents;
  54
  55   // FYI: Do NOT add any more friends here. The functions above are the ONLY
  56   // ones that need to call AttachTabHelpers; if you think you do, re-read the
  57   // design document linked above, especially the section "Reusing tab helpers".
  58
  59   // Adopts the specified WebContents as a full-fledged browser tab, attaching
  60   // all the associated tab helpers that are needed for the WebContents to
  61   // serve in that role. It is safe to call this on a WebContents that was
  62   // already adopted.
  63   static void AttachTabHelpers(content::WebContents* web_contents);
  64 };
  65
  66 #endif  // CHROME_BROWSER_UI_TAB_HELPERS_H_