Adds a field trial to control Web API kill switches.

chrome/browser/permissions/permission_context_base.h

 // 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.
 
 #ifndef CHROME_BROWSER_PERMISSIONS_PERMISSION_CONTEXT_BASE_H_
 #define CHROME_BROWSER_PERMISSIONS_PERMISSION_CONTEXT_BASE_H_
 
 #include "base/callback.h"
 #include "base/containers/scoped_ptr_hash_map.h"
 #include "base/memory/ref_counted.h"
@@ skipping 38 matching lines @@
 // It is mandatory to override IsRestrictedToSecureOrigin.
 // See midi_permission_context.h/cc or push_permission_context.cc/h for some
 // examples.
 
 class PermissionContextBase : public KeyedService {
  public:
   PermissionContextBase(Profile* profile,
                         const ContentSettingsType permission_type);
   ~PermissionContextBase() override;
 
+  // A field trial used to enable thw global API kill switch.

[raymes, 2015/10/13 01:30:18]

nit: thw->the

[kcarattini, 2015/10/13 03:06:22]

Done.

+  static const char kApiKillSwitchFieldStudy[];
+
+  // The field trial param to enable an API kill switch.
+  static const char kApiKillSwitchFieldParamEnabledValue[];

[raymes, 2015/10/13 01:30:18]

nit: you've referred to the kill switch in two different ways in the comments
which makes it sound a bit like they are two different things (the global API
kill switch vs. an API kill switch). Perhaps just refer to both as "an API kill
switch"? (or maybe I'm missing some more complexity here :)

[kcarattini, 2015/10/13 03:06:22]

I made them both "global. I want to distinguish this kill switch from the
origin-specific one that we;ll do for Safe Browsing.

+
   // The renderer is requesting permission to push messages.
   // When the answer to a permission request has been determined, |callback|
   // should be called with the result.
   virtual void RequestPermission(content::WebContents* web_contents,
                                  const PermissionRequestID& id,
                                  const GURL& requesting_frame,
                                  bool user_gesture,
                                  const BrowserPermissionCallback& callback);
 
   // Returns whether the permission has been granted, denied...
   virtual ContentSetting GetPermissionStatus(
       const GURL& requesting_origin,
       const GURL& embedding_origin) const;
 
   // Resets the permission to its default value.
   virtual void ResetPermission(const GURL& requesting_origin,
                                const GURL& embedding_origin);
 
   // Withdraw an existing permission request, no op if the permission request
   // was already cancelled by some other means.
   virtual void CancelPermissionRequest(content::WebContents* web_contents,
                                        const PermissionRequestID& id);
 
+  // Whether the kill switch has been enabled for this API.
+  virtual bool IsApiKillSwitchOn() const;
+
  protected:
   // Decide whether the permission should be granted.
   // Calls PermissionDecided if permission can be decided non-interactively,
   // or NotifyPermissionSet if permission decided by presenting an infobar.
   virtual void DecidePermission(content::WebContents* web_contents,
                                 const PermissionRequestID& id,
                                 const GURL& requesting_origin,
                                 const GURL& embedding_origin,
                                 bool user_gesture,
                                 const BrowserPermissionCallback& callback);
@@ skipping 44 matching lines @@
   scoped_ptr<PermissionQueueController> permission_queue_controller_;
   base::ScopedPtrHashMap<std::string, scoped_ptr<PermissionBubbleRequest>>
       pending_bubbles_;
 
   // Must be the last member, to ensure that it will be
   // destroyed first, which will invalidate weak pointers
   base::WeakPtrFactory<PermissionContextBase> weak_factory_;
 };
 
 #endif  // CHROME_BROWSER_PERMISSIONS_PERMISSION_CONTEXT_BASE_H_