Add plumbing to webRequest API to support event filtering.

This introduces a new kind of event (WebRequestEvent) to handle the extra parameters to addListener. Behind the scenes, adding a listener creates a unique sub-event associated with that set of filter+extraInfo parameters. When we dispatch the event, we dispatch only those sub-events that match the required filters.

BUG=60101
TEST=no

Review URL: http://codereview.chromium.org/6250152

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@74887 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 66 insertions, 2 deletions

diff --git a/chrome/renderer/resources/extension_process_bindings.js b/chrome/renderer/resources/extension_process_bindings.js
index f09b40a..d6e08fe 100644
--- a/chrome/renderer/resources/extension_process_bindings.js
+++ b/chrome/renderer/resources/extension_process_bindings.js
@@ -18,6 +18,7 @@ var chrome = chrome || {};
   native function SetIconCommon();
   native function IsExtensionProcess();
   native function IsIncognitoProcess();
+  native function GetUniqueSubEventName(eventName);
 
   var chromeHidden = GetChromeHidden();
 
@@ -234,6 +235,63 @@ var chrome = chrome || {};
 
   // --- Setup additional api's not currently handled in common/extensions/api
 
+  // WebRequestEvent object. This is used for special webRequest events with
+  // extra parameters. Each invocation of addListener creates a new named
+  // sub-event. That sub-event is associated with the extra parameters in the
+  // browser process, so that only it is dispatched when the main event occurs
+  // matching the extra parameters.
+  //
+  // Example:
+  //   chrome.webRequest.onBeforeRequest.addListener(
+  //       callback, {urls: "http://*.google.com/*"});
+  //   ^ callback will only be called for onBeforeRequests matching the filter.
+  chrome.WebRequestEvent = function(eventName, opt_argSchemas) {
+    if (typeof eventName != "string")
+      throw new Error("chrome.WebRequestEvent requires an event name.");
+
+    this.eventName_ = eventName;
+    this.argSchemas_ = opt_argSchemas;
+    this.subEvents_ = [];
+  };
+
+  // Registers a callback to be called when this event is dispatched. If
+  // opt_filter is specified, then the callback is only called for events that
+  // match the given filters. If opt_extraInfo is specified, the given optional
+  // info is sent to the callback.
+  chrome.WebRequestEvent.prototype.addListener =
+      function(cb, opt_filter, opt_extraInfo) {
+    var subEventName = GetUniqueSubEventName(this.eventName_);
+    // Note: this could fail to validate, in which case we would not add the
+    // subEvent listener.
+    chrome.experimental.webRequest.addEventListener(
+        cb, opt_filter, opt_extraInfo, this.eventName_, subEventName);
+
+    var subEvent = new chrome.Event(subEventName, this.argSchemas_);
+    this.subEvents_.push(subEvent);
+    subEvent.addListener(cb);
+  };
+
+  // Unregisters a callback.
+  chrome.WebRequestEvent.prototype.removeListener = function(cb) {
+    var idx = this.findListener_(cb);
+    if (idx >= -1) {
+      return;
+    }
+
+    this.subEvents_[idx].removeListener(cb);
+    if (!this.subEvents_[idx].hasListeners())
+      this.subEvents_.splice(idx, 1);
+  };
+
+  chrome.WebRequestEvent.prototype.findListener_ = function(cb) {
+    for (var i = 0; i < this.subEvents_.length; i++) {
+      if (this.subEvents_[i].findListener_(cb) > -1)
+        return i;
+    }
+
+    return -1;
+  };
+
   // Page action events send (pageActionId, {tabId, tabUrl}).
   function setupPageActionEvents(extensionId) {
     var pageActions = GetCurrentPageActions(extensionId);
@@ -442,8 +500,14 @@ var chrome = chrome || {};
             return;
 
           var eventName = apiDef.namespace + "." + eventDef.name;
-          module[eventDef.name] = new chrome.Event(eventName,
-              eventDef.parameters);
+          if (apiDef.namespace == "experimental.webRequest") {
+            // WebRequest events have a special structure.
+            module[eventDef.name] = new chrome.WebRequestEvent(eventName,
+                eventDef.parameters);
+          } else {
+            module[eventDef.name] = new chrome.Event(eventName,
+                eventDef.parameters);
+          }
         });
       }