[Mac] Support windowless Flash plugin rendering directly to the context for single-process apps

webkit/plugins/npapi/webplugin_delegate_impl_mac.mm

Index: webkit/plugins/npapi/webplugin_delegate_impl_mac.mm
===================================================================
--- webkit/plugins/npapi/webplugin_delegate_impl_mac.mm	(revision 98412)
+++ webkit/plugins/npapi/webplugin_delegate_impl_mac.mm	(working copy)
@@ -262,6 +262,7 @@
       instance_(instance),
       parent_(containing_view),
       quirks_(0),
+      use_buffer_context_(true),
       buffer_context_(NULL),
       layer_(nil),
       surface_(NULL),
@@ -692,18 +693,24 @@
                                             const gfx::Rect& damage_rect) {
   // If we get a paint event before we are completely set up (e.g., a nested
   // call while the plugin is still in NPP_SetWindow), bail.
-  if (!have_called_set_window_ || !buffer_context_)
+  if (!have_called_set_window_ || (use_buffer_context_ && !buffer_context_))
     return;
-  DCHECK(buffer_context_ == context);
+  DCHECK(!use_buffer_context_ || buffer_context_ == context);
 
   static base::StatsRate plugin_paint("Plugin.Paint");
   base::StatsScope<base::StatsRate> scope(plugin_paint);
 
-  // Plugin invalidates trigger asynchronous paints with the original
-  // invalidation rect; the plugin may be resized before the paint is handled,
-  // so we need to ensure that the damage rect is still sane.
-  const gfx::Rect paint_rect(damage_rect.Intersect(
-      gfx::Rect(0, 0, window_rect_.width(), window_rect_.height())));
+  gfx::Rect paint_rect;
+  if (use_buffer_context_) {
+    // Plugin invalidates trigger asynchronous paints with the original
+    // invalidation rect; the plugin may be resized before the paint is handled,
+    // so we need to ensure that the damage rect is still sane.
+    paint_rect = damage_rect.Intersect(
+        gfx::Rect(0, 0, window_rect_.width(), window_rect_.height()));
+  } else {
+    // Use the actual window region when drawing directly to the window context.
+    paint_rect = damage_rect.Intersect(window_rect_);
+  }
 
   ScopedActiveDelegate active_delegate(this);
 
@@ -714,6 +721,13 @@
 
   CGContextSaveGState(context);
 
+  if (!use_buffer_context_) {
+    // Reposition the context origin so that plugins will draw at the correct
+    // location in the window.
+    CGContextClipToRect(context, paint_rect.ToCGRect());
+    CGContextTranslateCTM(context, window_rect_.x(), window_rect_.y());
+  }
+
   switch (instance()->event_model()) {
 #ifndef NP_NO_CARBON
     case NPEventModelCarbon: {
@@ -739,10 +753,15 @@
     }
   }
 
-  // The backing buffer can change during the call to NPP_HandleEvent, in which
-  // case the old context is (or is about to be) invalid.
-  if (context == buffer_context_)
+  if (use_buffer_context_) {
+    // The backing buffer can change during the call to NPP_HandleEvent, in
+    // which case the old context is (or is about to be) invalid.
+    if (context == buffer_context_)
+      CGContextRestoreGState(context);
+  } else {
+    // Always restore the context to the saved state.
     CGContextRestoreGState(context);
+  }
 }
 
 void WebPluginDelegateImpl::WindowlessSetWindow() {
@@ -1115,6 +1134,10 @@
                                                             plugin_visible);
 }
 
+void WebPluginDelegateImpl::SetNoBufferContext() {
+  use_buffer_context_ = false;
+}
+
 void WebPluginDelegateImpl::FireIdleEvent() {
   // Avoid a race condition between IO and UI threads during plugin shutdown
   if (!instance())