Support for interactive set-chrome-as-default in Windows.

chrome/browser/shell_integration.h

 // 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.
 
 #ifndef CHROME_BROWSER_SHELL_INTEGRATION_H_
 #define CHROME_BROWSER_SHELL_INTEGRATION_H_
 #pragma once
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/file_path.h"
 #include "base/memory/ref_counted.h"
 #include "base/string16.h"
 #include "googleurl/src/gurl.h"
 #include "ui/gfx/image/image.h"
 
 class CommandLine;
 
 class ShellIntegration {
  public:
   // Sets Chrome as the default browser (only for the current user). Returns
   // false if this operation fails.
   static bool SetAsDefaultBrowser();
 
+  // Initiates an OS shell flow which (if followed by the user) should set
+  // Chrome as the default browser. Returns false if the flow cannot be
+  // initialized, if it is not supported (introduced for Windows 8) or if the
+  // user cancels the operation. This is a blocking call and requires a FILE
+  // thread.
+  static bool SetAsDefaultBrowserInteractive();
+
   // Sets Chrome as the default client application for the given protocol
   // (only for the current user). Returns false if this operation fails.
   static bool SetAsDefaultProtocolClient(const std::string& protocol);
 
-  // Returns true if the running browser can be set as the default browser.
-  static bool CanSetAsDefaultBrowser();
+  // In Windows 8 a browser can be made default-in-metro only in an interactive
+  // flow. We will distinguish between two types of permissions here to avoid
+  // forcing the user into UI interaction when this should not be done.
+  enum DefaultWebClientSetPermission {
+    SET_DEFAULT_NOT_ALLOWED = 0,
+    SET_DEFAULT_UNATTENDED,
+    SET_DEFAULT_INTERACTIVE,
+  };
 
-  // Returns true if the running browser can be set as the default client
-  // application for specific protocols.
-  static bool CanSetAsDefaultProtocolClient();
+  // Returns requirements for making the running browser the user's default.
+  static DefaultWebClientSetPermission CanSetAsDefaultBrowser();
+
+  // Returns requirements for making the running browser the user's default
+  // client application for specific protocols.
+  static DefaultWebClientSetPermission CanSetAsDefaultProtocolClient();
 
   // On Linux, it may not be possible to determine or set the default browser
   // on some desktop environments or configurations. So, we use this enum and
   // not a plain bool. (Note however that if used like a bool, this enum will
   // have reasonable behavior.)
   enum DefaultWebClientState {
     NOT_DEFAULT_WEB_CLIENT = 0,
     IS_DEFAULT_WEB_CLIENT,
     UNKNOWN_DEFAULT_WEB_CLIENT = -1
   };
@@ skipping 97 matching lines @@
   };
 
   class DefaultWebClientObserver {
    public:
     virtual ~DefaultWebClientObserver() {}
     // Updates the UI state to reflect the current default browser state.
     virtual void SetDefaultWebClientUIState(DefaultWebClientUIState state) = 0;
     // Observer classes that return true to OwnedByWorker are automatically
     // freed by the worker when they are no longer needed.
     virtual bool IsOwnedByWorker() { return false; }
+    // An observer can permit or decline set-as-default operation if it
+    // requires triggering user interaction.
+    virtual bool IsInteractiveSetDefaultPermitted() { return false; }
   };
 
   //  Helper objects that handle checking if Chrome is the default browser
   //  or application for a url protocol on Windows and Linux, and also setting
   //  it as the default. These operations are performed asynchronously on the
   //  file thread since registry access (on Windows) or the preference database
   //  (on Linux) are involved and this can be slow.
   class DefaultWebClientWorker
       : public base::RefCountedThreadSafe<DefaultWebClientWorker> {
    public:
@@ skipping 15 matching lines @@
    protected:
     friend class base::RefCountedThreadSafe<DefaultWebClientWorker>;
 
     virtual ~DefaultWebClientWorker() {}
 
    private:
     // Function that performs the check.
     virtual DefaultWebClientState CheckIsDefault() = 0;
 
     // Function that sets Chrome as the default web client.
-    virtual void SetAsDefault() = 0;
+    virtual void SetAsDefault(bool interactive_permitted) = 0;
 
     // Function that handles performing the check on the file thread. This
     // function is posted as a task onto the file thread, where it performs
     // the check. When the check has finished the CompleteCheckIsDefault
     // function is posted to the UI thread, where the result is sent back to
     // the observer.
     void ExecuteCheckIsDefault();
 
     // Function that handles setting Chrome as the default web client on the
     // file thread. This function is posted as a task onto the file thread.
@@ skipping 28 matching lines @@
    public:
     explicit DefaultBrowserWorker(DefaultWebClientObserver* observer);
 
    private:
     virtual ~DefaultBrowserWorker() {}
 
     // Check if Chrome is the default browser.
     virtual DefaultWebClientState CheckIsDefault() OVERRIDE;
 
     // Set Chrome as the default browser.
-    virtual void SetAsDefault() OVERRIDE;
+    virtual void SetAsDefault(bool interactive_permitted) OVERRIDE;
 
     DISALLOW_COPY_AND_ASSIGN(DefaultBrowserWorker);
   };
 
   // Worker for checking and setting the default client application
   // for a given protocol. A different worker instance is needed for each
   // protocol you are interested in, so to check or set the default for
   // multiple protocols you should use multiple worker objects.
   class DefaultProtocolClientWorker : public DefaultWebClientWorker {
    public:
     DefaultProtocolClientWorker(DefaultWebClientObserver* observer,
                                 const std::string& protocol);
 
     const std::string& protocol() const { return protocol_; }
 
    protected:
     virtual ~DefaultProtocolClientWorker() {}
 
    private:
     // Check is Chrome is the default handler for this protocol.
     virtual DefaultWebClientState CheckIsDefault() OVERRIDE;
 
     // Set Chrome as the default handler for this protocol.
-    virtual void SetAsDefault() OVERRIDE;
+    virtual void SetAsDefault(bool interactive_permitted) OVERRIDE;
 
     std::string protocol_;
 
     DISALLOW_COPY_AND_ASSIGN(DefaultProtocolClientWorker);
   };
 };
 
 #endif  // CHROME_BROWSER_SHELL_INTEGRATION_H_