<webview>: First stab at implementing media permission request for guests.

content/renderer/browser_plugin/browser_plugin.cc

Index: content/renderer/browser_plugin/browser_plugin.cc
diff --git a/content/renderer/browser_plugin/browser_plugin.cc b/content/renderer/browser_plugin/browser_plugin.cc
index 033330beb599edd8573bef41fd3c71d384f2c2a9..f1e8f8f267a1f43b4307b88e48d1a9e7d7162771 100644
--- a/content/renderer/browser_plugin/browser_plugin.cc
+++ b/content/renderer/browser_plugin/browser_plugin.cc
@@ -54,6 +54,7 @@ const char kEventLoadCommit[] = "loadcommit";
 const char kEventLoadRedirect[] = "loadredirect";
 const char kEventLoadStart[] = "loadstart";
 const char kEventLoadStop[] = "loadstop";
+const char kEventRequestPermission[] = "permissionrequest";
 const char kEventResponsive[] = "responsive";
 const char kEventSizeChanged[] = "sizechanged";
 const char kEventUnresponsive[] = "unresponsive";
@@ -67,9 +68,12 @@ const char kOldURL[] = "oldUrl";
 const char kOldHeight[] = "oldHeight";
 const char kOldWidth[] = "oldWidth";
 const char kPartition[] = "partition";
+const char kPermission[] = "permission";
+const char kPermissionTypeMedia[] = "media";
 const char kPersistPrefix[] = "persist:";
 const char kProcessId[] = "processId";
 const char kReason[] = "reason";
+const char kRequestId[] = "request_id";
 const char kSrc[] = "src";
 const char kURL[] = "url";
 
@@ -678,6 +682,41 @@ void BrowserPlugin::LoadAbort(const GURL& url,
   TriggerEvent(kEventLoadAbort, &props);
 }
 
+void BrowserPlugin::RequestMediaAccess(int request_id,
+                                       const GURL& security_origin) {
+  size_t num_listeners = GetNumberOfEventListeners(kEventRequestPermission);
+  if (!num_listeners) {
+    // Automatically deny the request if there are no event listeners for
+    // permissionrequest.
+    RespondMediaAccess(request_id, false /* allow */);
+    return;
+  }
+  DCHECK(media_access_pending_counts_.find(request_id) ==
+         media_access_pending_counts_.end());
+  media_access_pending_counts_[request_id] = num_listeners;
+
+  std::map<std::string, base::Value*> props;
+  props[kPermission] = base::Value::CreateStringValue(kPermissionTypeMedia);
+  props[kRequestId] = base::Value::CreateIntegerValue(request_id);
+  props[kURL] = base::Value::CreateStringValue(security_origin.spec());
+  TriggerEvent(kEventRequestPermission, &props);
+}
+
+size_t BrowserPlugin::GetNumberOfEventListeners(const std::string& event_name) {
+  if (!container())
+    return 0;
+
+  WebKit::WebNode parent = container()->element().parentNode();
+  if (!parent.isNull() && parent.isShadowRoot()) {
+    WebKit::WebElement shadow_host = parent.shadowHost();
+    if (!shadow_host.isNull()) {
+      return shadow_host.numberOfEventListeners(
+          WebKit::WebString::fromUTF8(event_name));
+    }
+  }
+  return 0;
+}
+
 void BrowserPlugin::LoadRedirect(const GURL& old_url,
                                  const GURL& new_url,
                                  bool is_top_level) {
@@ -731,6 +770,34 @@ void BrowserPlugin::SetAcceptTouchEvents(bool accept) {
   }
 }
 
+void BrowserPlugin::RespondMediaAccess(int request_id, bool allow) {
+  browser_plugin_manager()->Send(
+      new BrowserPluginHostMsg_AllowMediaAccess(render_view_->GetRoutingID(),
+                                                instance_id_,
+                                                request_id,
+                                                allow));
+}
+
+void BrowserPlugin::OnListenerCallMediaAccess(int request_id, bool allow) {
+  MediaAccessPendingCountsMap::iterator iter =
+      media_access_pending_counts_.find(request_id);
+  if (iter == media_access_pending_counts_.end())
+    return;
+  DCHECK(iter->second > 0);
+  // If there were n listeners registered for media access permissionrequest, we
+  // require n allow() calls to allow the request.
+  // TODO(lazyboy): Figure out a way to track that each listener calls allow()
+  // at least once. Right now we only check for total number of allow() calls,
+  // which means a single listener calling allow() enough/multiple times can
+  // incorrectly allow the request.

[Charlie Reis, 2012/12/17 22:28:09]

Yeah, that's no good.  Ideally there would be some way to match up the responses
to the functions we handed out, like keeping a reference to each allow/deny
function.  An unforgeable ID (e.g., in the function's closure) would also be
sufficient.  I don't know how we can get TriggerEvent to hand out a different
version of the function to each listener, though.

We may need some advice on this, since it's an important aspect of the API if we
stick with this design.  Not sure I'm comfortable leaving it as a TODO without a
plan for how to fix it.

+  if (!allow || iter->second == 1) {
+    media_access_pending_counts_.erase(iter);
+    RespondMediaAccess(request_id, allow);
+  } else {
+    iter->second--;
+  }
+}
+
 WebKit::WebPluginContainer* BrowserPlugin::container() const {
   return container_;
 }