Remove the carbon event dispatcher from the main thread of the plugin process

and replace it with a pump for null events on the plugin thread.  This removes
a deadlock that the previous code inadvertently created, and is a much more
focused solution to the problem.
BUG=10809
TEST=none

Review URL: http://codereview.chromium.org/155439

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@20528 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 31 insertions, 55 deletions

diff --git a/chrome/plugin/plugin_main.cc b/chrome/plugin/plugin_main.cc
index 4cc7911..375831a 100644
--- a/chrome/plugin/plugin_main.cc
+++ b/chrome/plugin/plugin_main.cc
@@ -27,47 +27,6 @@
 #include "base/global_descriptors_posix.h"
 #endif
 
-#if defined(OS_MACOSX)
-
-// To support Mac NPAPI plugins that use the Carbon event model (i.e., most
-// shipping plugins for MacOS X 10.5 and earlier), we need some way for the
-// Carbon event dispatcher to run, even though the plugin host process itself
-// does not use Carbon events.  Rather than give control to the standard
-// Carbon event loop, we schedule a periodic task on the main thread which
-// empties the Carbon event queue every 20ms (chosen to match how often Safari
-// does the equivalent operation).  This allows plugins to receive idle events
-// and schedule Carbon timers without swamping the CPU.  If, in the future,
-// we remove support for the Carbon event model and only support the Cocoa
-// event model, this can be removed.  Note that this approach does not install
-// standard application event handlers for the menubar, AppleEvents, and so on.
-// This is intentional, since the plugin process is not actually an application
-// with its own UI elements--all rendering and event handling happens via IPC
-// to the renderer process which invoked it.
-
-namespace {
-
-const int kPluginUpdateIntervalMs = 20; // 20ms = 50Hz
-
-void PluginCarbonEventTask() {
-  EventRef theEvent;
-  EventTargetRef theTarget;
-
-  theTarget = GetEventDispatcherTarget();
-
-  // Dispatch any pending events. but do not block if there are no events.
-  while (ReceiveNextEvent(0, NULL, kEventDurationNoWait,
-                          true, &theEvent) == noErr) {
-    SendEventToEventTarget (theEvent, theTarget);
-    ReleaseEvent(theEvent);
-  }
-
-  MessageLoop::current()->PostDelayedTask(FROM_HERE,
-      NewRunnableFunction(PluginCarbonEventTask), kPluginUpdateIntervalMs);
-}
-
-}
-#endif
-
 // main() routine for running as the plugin process.
 int PluginMain(const MainFunctionParams& parameters) {
   // The main thread of the plugin services IO.
@@ -120,13 +79,6 @@ int PluginMain(const MainFunctionParams& parameters) {
 #endif
   }
 
-#if defined(OS_MACOSX)
-  // Spin off a consumer for the native (Carbon) event stream so
-  // that plugin timers, event handlers, etc. will work properly.
-  MessageLoop::current()->PostDelayedTask(FROM_HERE,
-      NewRunnableFunction(PluginCarbonEventTask), kPluginUpdateIntervalMs);
-#endif
-
   {
     ChildProcess plugin_process(new PluginThread());
 #if defined(OS_WIN)
diff --git a/webkit/glue/plugins/webplugin_delegate_impl.h b/webkit/glue/plugins/webplugin_delegate_impl.h
index 35302dc7..4d928ab 100644
--- a/webkit/glue/plugins/webplugin_delegate_impl.h
+++ b/webkit/glue/plugins/webplugin_delegate_impl.h
@@ -272,6 +272,14 @@ class WebPluginDelegateImpl : public WebPluginDelegate {
   static HCURSOR WINAPI SetCursorPatch(HCURSOR cursor);
 #endif
 
+#if defined(OS_MACOSX)
+  // Runnable Method Factory used to drip null events into the plugin
+  ScopedRunnableMethodFactory<WebPluginDelegateImpl> null_event_factory_;
+
+  // indicates that it's time to send the plugin a null event
+  void OnNullEvent();
+#endif
+
   // Holds the current cursor set by the windowless plugin.
   WebCursor current_windowless_cursor_;
 
diff --git a/webkit/glue/plugins/webplugin_delegate_impl_mac.mm b/webkit/glue/plugins/webplugin_delegate_impl_mac.mm
index 9232fca..c6d0d5a 100644
--- a/webkit/glue/plugins/webplugin_delegate_impl_mac.mm
+++ b/webkit/glue/plugins/webplugin_delegate_impl_mac.mm
@@ -38,16 +38,15 @@ using WebKit::WebMouseEvent;
 
 namespace {
 
-// The fastest we are willing to process idle events for Flash.
-// Flash can easily exceed the limits of our CPU if we don't throttle it.
-// The throttle has been chosen by testing various delays and compromising
-// on acceptable Flash performance and reasonable CPU consumption.
+// The fastest we are willing to process idle events for plugins.
+// Some can easily exceed the limits of our CPU if we don't throttle them.
+// The throttle has been chosen by using the same value as Apple's WebKit port.
 //
 // We'd like to make the throttle delay variable, based on the amount of
-// time currently required to paint Flash plugins.  There isn't a good
+// time currently required to paint plugins.  There isn't a good
 // way to count the time spent in aggregate plugin painting, however, so
 // this seems to work well enough.
-const int kFlashIdleThrottleDelayMs = 20;  // 20ms (50Hz)
+const int kPluginIdleThrottleDelayMs = 20;  // 20ms (50Hz)
 
 // The current instance of the plugin which entered the modal loop.
 WebPluginDelegateImpl* g_current_plugin_instance = NULL;
@@ -84,7 +83,8 @@ WebPluginDelegateImpl::WebPluginDelegateImpl(
       windowless_needs_set_window_(true),
       handle_event_depth_(0),
       user_gesture_message_posted_(this),
-      user_gesture_msg_factory_(this) {
+      user_gesture_msg_factory_(this),
+      null_event_factory_(this) {
   memset(&window_, 0, sizeof(window_));
 }
 
@@ -126,6 +126,10 @@ bool WebPluginDelegateImpl::Initialize(const GURL& url,
   plugin->SetWindow(NULL);
   plugin_url_ = url.spec();
 
+  MessageLoop::current()->PostDelayedTask(FROM_HERE,
+      null_event_factory_.NewRunnableMethod(
+          &WebPluginDelegateImpl::OnNullEvent),
+      kPluginIdleThrottleDelayMs);
   return true;
 }
 
@@ -507,3 +511,15 @@ void WebPluginDelegateImpl::URLRequestRouted(const std::string&url,
     instance()->SetURLLoadData(GURL(url.c_str()), notify_data);
   }
 }
+
+void WebPluginDelegateImpl::OnNullEvent() {
+  NPEvent np_event = {0};
+  np_event.what = nullEvent;
+  np_event.when = TickCount();
+  instance()->NPP_HandleEvent(&np_event);
+
+  MessageLoop::current()->PostDelayedTask(FROM_HERE,
+      null_event_factory_.NewRunnableMethod(
+          &WebPluginDelegateImpl::OnNullEvent),
+      kPluginIdleThrottleDelayMs);
+}