nsIWebProgressListener Interface

 The nsIWebProgressListener interface is implemented by clients wishing to
 listen in on the progress associated with the loading of asynchronous
 requests in the context of a nsIWebProgress instance as well as any child
 nsIWebProgress instances.  nsIWebProgress.idl describes the parent-child
 relationship of nsIWebProgress instances.

 @status FROZEN

[scriptable, uuid(570f39d1-efd0-11d3-b093-00a024ffc08c)]

Constants

 State Transition Flags

 These flags indicate the various states that requests may transition
 through as they are being loaded.  These flags are mutually exclusive.

 For any given request, onStateChange is called once with the STATE_START
 flag, zero or more times with the STATE_TRANSFERRING flag or once with the
 STATE_REDIRECTING flag, and then finally once with the STATE_STOP flag.
 NOTE: For document requests, a second STATE_STOP is generated (see the
 description of STATE_IS_WINDOW for more details).

 STATE_START
   This flag indicates the start of a request.  This flag is set when a
   request is initiated.  The request is complete when onStateChange is
   called for the same request with the STATE_STOP flag set.

 STATE_REDIRECTING
   This flag indicates that a request is being redirected.  The request
   passed to onStateChange is the request that is being redirected.  When a
   redirect occurs, a new request is generated automatically to process the
   new request.  Expect a corresponding STATE_START event for the new
   request, and a STATE_STOP for the redirected request.

 STATE_TRANSFERRING
   This flag indicates that data for a request is being transferred to an
   end consumer.  This flag indicates that the request has been targeted,
   and that the user may start seeing content corresponding to the request.

 STATE_NEGOTIATING
   This flag is not used.

 STATE_STOP
   This flag indicates the completion of a request.  The aStatus parameter
   to onStateChange indicates the final status of the request.

const unsigned long STATE_START = 1

const unsigned long STATE_REDIRECTING = 2

const unsigned long STATE_TRANSFERRING = 4

const unsigned long STATE_NEGOTIATING = 8

const unsigned long STATE_STOP = 16

 State Type Flags

 These flags further describe the entity for which the state transition is
 occuring.  These flags are NOT mutually exclusive (i.e., an onStateChange
 event may indicate some combination of these flags).

 STATE_IS_REQUEST
   This flag indicates that the state transition is for a request, which
   includes but is not limited to document requests.  (See below for a
   description of document requests.)  Other types of requests, such as
   requests for inline content (e.g., images and stylesheets) are
   considered normal requests.

 STATE_IS_DOCUMENT
   This flag indicates that the state transition is for a document request.
   This flag is set in addition to STATE_IS_REQUEST.  A document request
   supports the nsIChannel interface and its loadFlags attribute includes
   the nsIChannel::LOAD_DOCUMENT_URI flag.
 
   A document request does not complete until all requests associated with
   the loading of its corresponding document have completed.  This includes
   other document requests (e.g., corresponding to HTML <iframe> elements).
   The document corresponding to a document request is available via the
   DOMWindow attribute of onStateChange's aWebProgress parameter.

 STATE_IS_NETWORK
   This flag indicates that the state transition corresponds to the start
   or stop of activity in the indicated nsIWebProgress instance.  This flag
   is accompanied by either STATE_START or STATE_STOP, and it may be
   combined with other State Type Flags.

   Unlike STATE_IS_WINDOW, this flag is only set when activity within the
   nsIWebProgress instance being observed starts or stops.  If activity
   only occurs in a child nsIWebProgress instance, then this flag will be
   set to indicate the start and stop of that activity.

   For example, in the case of navigation within a single frame of a HTML
   frameset, a nsIWebProgressListener instance attached to the
   nsIWebProgress of the frameset window will receive onStateChange calls
   with the STATE_IS_NETWORK flag set to indicate the start and stop of
   said navigation.  In other words, an observer of an outer window can
   determine when activity, that may be constrained to a child window or
   set of child windows, starts and stops.

 STATE_IS_WINDOW
   This flag indicates that the state transition corresponds to the start
   or stop of activity in the indicated nsIWebProgress instance.  This flag
   is accompanied by either STATE_START or STATE_STOP, and it may be
   combined with other State Type Flags.

   This flag is similar to STATE_IS_DOCUMENT.  However, when a document
   request completes, two onStateChange calls with STATE_STOP are
   generated.  The document request is passed as aRequest to both calls.
   The first has STATE_IS_REQUEST and STATE_IS_DOCUMENT set, and the second
   has the STATE_IS_WINDOW flag set (and possibly the STATE_IS_NETWORK flag
   set as well -- see above for a description of when the STATE_IS_NETWORK
   flag may be set).  This second STATE_STOP event may be useful as a way
   to partition the work that occurs when a document request completes.

const unsigned long STATE_IS_REQUEST = 65536

const unsigned long STATE_IS_DOCUMENT = 131072

const unsigned long STATE_IS_NETWORK = 262144

const unsigned long STATE_IS_WINDOW = 524288

 State Modifier Flags

 These flags further describe the transition which is occuring.  These
 flags are NOT mutually exclusive (i.e., an onStateChange event may
 indicate some combination of these flags).

 STATE_RESTORING
   This flag indicates that the state transition corresponds to the start
   or stop of activity for restoring a previously-rendered presentation.
   As such, there is no actual network activity associated with this
   request, and any modifications made to the document or presentation
   when it was originally loaded will still be present.

const unsigned long STATE_RESTORING = 16777216

 State Security Flags

 These flags describe the security state reported by a call to the
 onSecurityChange method.  These flags are mutually exclusive.

 STATE_IS_INSECURE
   This flag indicates that the data corresponding to the request
   was received over an insecure channel.

 STATE_IS_BROKEN
   This flag indicates an unknown security state.  This may mean that the
   request is being loaded as part of a page in which some content was
   received over an insecure channel.

 STATE_IS_SECURE
   This flag indicates that the data corresponding to the request was
   received over a secure channel.  The degree of security is expressed by
   STATE_SECURE_HIGH, STATE_SECURE_MED, or STATE_SECURE_LOW.

const unsigned long STATE_IS_INSECURE = 4

const unsigned long STATE_IS_BROKEN = 1

const unsigned long STATE_IS_SECURE = 2

 Security Strength Flags

 These flags describe the security strength and accompany STATE_IS_SECURE
 in a call to the onSecurityChange method.  These flags are mutually
 exclusive.

 These flags are not meant to provide a precise description of data
 transfer security.  These are instead intended as a rough indicator that
 may be used to, for example, color code a security indicator or otherwise
 provide basic data transfer security feedback to the user.

 STATE_SECURE_HIGH
   This flag indicates a high degree of security.

 STATE_SECURE_MED
   This flag indicates a medium degree of security.

 STATE_SECURE_LOW
   This flag indicates a low degree of security.

const unsigned long STATE_SECURE_HIGH = 262144

const unsigned long STATE_SECURE_MED = 65536

const unsigned long STATE_SECURE_LOW = 131072

 State bits for EV == Extended Validation == High Assurance

 These flags describe the level of identity verification
 in a call to the onSecurityChange method. 

 STATE_IDENTITY_EV_TOPLEVEL
   The topmost document uses an EV cert.
   NOTE: Available since Gecko 1.9

const unsigned long STATE_IDENTITY_EV_TOPLEVEL = 1048576

Methods

 Called when the location of the window being watched changes.  This is not
 when a load is requested, but rather once it is verified that the load is
 going to occur in the given window.  For instance, a load that starts in a
 window might send progress and status messages for the new site, but it
 will not send the onLocationChange until we are sure that we are loading
 this new page here.

 @param aWebProgress
        The nsIWebProgress instance that fired the notification.
 @param aRequest
        The associated nsIRequest.  This may be null in some cases.
 @param aLocation
        The URI of the location that is being loaded.

void onLocationChange(in nsIWebProgress aWebProgress, in nsIRequest aRequest, in nsIURI aLocation)

 Notification that the progress has changed for one of the requests
 associated with aWebProgress.  Progress totals are reset to zero when all
 requests in aWebProgress complete (corresponding to onStateChange being
 called with aStateFlags including the STATE_STOP and STATE_IS_WINDOW
 flags).

 @param aWebProgress
        The nsIWebProgress instance that fired the notification.
 @param aRequest
        The nsIRequest that has new progress.
 @param aCurSelfProgress
        The current progress for aRequest.
 @param aMaxSelfProgress
        The maximum progress for aRequest.
 @param aCurTotalProgress
        The current progress for all requests associated with aWebProgress.
 @param aMaxTotalProgress
        The total progress for all requests associated with aWebProgress.

 NOTE: If any progress value is unknown, or if its value would exceed the
 maximum value of type long, then its value is replaced with -1.

 NOTE: If the object also implements nsIWebProgressListener2 and the caller
 knows about that interface, this function will not be called. Instead,
 nsIWebProgressListener2::onProgressChange64 will be called.

void onProgressChange(in nsIWebProgress aWebProgress, in nsIRequest aRequest, in long aCurSelfProgress, in long aMaxSelfProgress, in long aCurTotalProgress, in long aMaxTotalProgress)

 Notification called for security progress.  This method will be called on
 security transitions (eg HTTP -> HTTPS, HTTPS -> HTTP, FOO -> HTTPS) and
 after document load completion.  It might also be called if an error
 occurs during network loading.

 @param aWebProgress
        The nsIWebProgress instance that fired the notification.
 @param aRequest
        The nsIRequest that has new security state.
 @param aState
        A value composed of the Security State Flags and the Security
        Strength Flags listed above.  Any undefined bits are reserved for
        future use.

 NOTE: These notifications will only occur if a security package is
 installed.

void onSecurityChange(in nsIWebProgress aWebProgress, in nsIRequest aRequest, in unsigned long aState)

 Notification indicating the state has changed for one of the requests
 associated with aWebProgress.

 @param aWebProgress
        The nsIWebProgress instance that fired the notification
 @param aRequest
        The nsIRequest that has changed state.
 @param aStateFlags
        Flags indicating the new state.  This value is a combination of one
        of the State Transition Flags and one or more of the State Type
        Flags defined above.  Any undefined bits are reserved for future
        use.
 @param aStatus
        Error status code associated with the state change.  This parameter
        should be ignored unless aStateFlags includes the STATE_STOP bit.
        The status code indicates success or failure of the request
        associated with the state change.  NOTE: aStatus may be a success
        code even for server generated errors, such as the HTTP 404 error.
        In such cases, the request itself should be queried for extended
        error information (e.g., for HTTP requests see nsIHttpChannel).

void onStateChange(in nsIWebProgress aWebProgress, in nsIRequest aRequest, in unsigned long aStateFlags, in nsresult aStatus)

 Notification that the status of a request has changed.  The status message
 is intended to be displayed to the user (e.g., in the status bar of the
 browser).

 @param aWebProgress
        The nsIWebProgress instance that fired the notification.
 @param aRequest
        The nsIRequest that has new status.
 @param aStatus
        This value is not an error code.  Instead, it is a numeric value
        that indicates the current status of the request.  This interface
        does not define the set of possible status codes.  NOTE: Some
        status values are defined by nsITransport and nsISocketTransport.
 @param aMessage
        Localized text corresponding to aStatus.

void onStatusChange(in nsIWebProgress aWebProgress, in nsIRequest aRequest, in nsresult aStatus, in wstring aMessage)