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 DefaultSettingsChangePermission {

[gab, 2012/06/06 22:47:21]

This name "DefaultSettingsChangePermission" is very long and I don't feel it
conveys the advantage of a long name (i.e. its not really clear what it is from
the name anyways).

What about something like "MakeDefaultOption" or "MakeDefaultMode"?

and then change the names below to
MAKE_DEFAULT_*
as the intent is to *make* chrome default not *change* the default to a random
browser.

I'm open to replacing 'make' with set' in my above suggestions too (i.e. we have
SetDefault functions and MakeDefault functions in the code, but no ChangeDefault
functions).

[motek., 2012/06/07 14:58:50]

Nah. This type expresses neither mode nor defines an option. It defines a
response to 'can I make this default', so 'permission' seems to be the best word
here. 
DefaultWebClientSetPermission would not be much shorter, but perhaps more
illuminating than the current state or either of proposed alternatives. I'll
change to that.

+    CHANGE_DEFAULT_NOT_ALLOWED = 0,
+    CHANGE_DEFAULT_UNATTENDED,
+    CHANGE_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 DefaultSettingsChangePermission CanSetAsDefaultBrowser();
+
+  // Returns requirements for making the running browser the user's default
+  // client application for specific protocols.
+  static DefaultSettingsChangePermission 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_