Add some optimizations to plugin painting.

The simplest one is to disable blending when the plugin is opaque.

The more complicated one is to bypass webkit painting the background of plugins
when we know the plugin to be always on top and also opaque. The always on top
flag is currently set by a new "Private2" API. Bypassing WebKit makes
animations faster.

BUG=none
TEST=none
Review URL: http://codereview.chromium.org/3421030

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@60329 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 22 insertions, 5 deletions

diff --git a/chrome/renderer/render_widget.cc b/chrome/renderer/render_widget.cc
index 3252097..95346c3 100644
--- a/chrome/renderer/render_widget.cc
+++ b/chrome/renderer/render_widget.cc
@@ -505,11 +505,21 @@ void RenderWidget::DoDeferredUpdate() {
   gfx::Rect scroll_damage = update.GetScrollDamage();
   gfx::Rect bounds = update.GetPaintBounds().Union(scroll_damage);
 
+  // A plugin may be able to do an optimized paint. First check this, in which
+  // case we can skip all of the bitmap generation and regular paint code.
+  TransportDIB::Id dib_id;
+  TransportDIB* dib = NULL;
   std::vector<gfx::Rect> copy_rects;
-  if (!is_gpu_rendering_active_) {
+  if (update.scroll_rect.IsEmpty() &&
+      !is_gpu_rendering_active_ &&
+      GetBitmapForOptimizedPluginPaint(&bounds, &dib)) {
+    copy_rects.push_back(bounds);
+    dib_id = dib->id();
+  } else if (!is_gpu_rendering_active_) {
     // Compute a buffer for painting and cache it.
-    scoped_ptr<skia::PlatformCanvas> canvas
-      (RenderProcess::current()->GetDrawingCanvas(&current_paint_buf_, bounds));
+    scoped_ptr<skia::PlatformCanvas> canvas(
+        RenderProcess::current()->GetDrawingCanvas(&current_paint_buf_,
+                                                   bounds));
     if (!canvas.get()) {
       NOTREACHED();
       return;
@@ -538,6 +548,8 @@ void RenderWidget::DoDeferredUpdate() {
 
     for (size_t i = 0; i < copy_rects.size(); ++i)
       PaintRect(copy_rects[i], bounds.origin(), canvas.get());
+
+    dib_id = current_paint_buf_->id();
   } else {  // Accelerated compositing path
     // Begin painting.
     bool finish = next_paint_is_resize_ack();
@@ -546,8 +558,7 @@ void RenderWidget::DoDeferredUpdate() {
 
   // sending an ack to browser process that the paint is complete...
   ViewHostMsg_UpdateRect_Params params;
-  params.bitmap =
-      current_paint_buf_ ? current_paint_buf_->id() : TransportDIB::Id();
+  params.bitmap = dib_id;
   params.bitmap_rect = bounds;
   params.dx = update.scroll_delta.x();
   params.dy = update.scroll_delta.y();
@@ -889,6 +900,12 @@ void RenderWidget::OnSetTextDirection(WebTextDirection direction) {
   webwidget_->setTextDirection(direction);
 }
 
+bool RenderWidget::GetBitmapForOptimizedPluginPaint(gfx::Rect* bounds,
+                                                    TransportDIB** dib) {
+  // Normal RenderWidgets don't support optimized plugin painting.
+  return false;
+}
+
 void RenderWidget::SetHidden(bool hidden) {
   if (is_hidden_ == hidden)
     return;