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.

This is a re-land of the previous patch with a trivial compilation fix. This
also adds a clip rect to the GetBitmap... function so we can properly handle
plugins in nested iframes with proper clipping.

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

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@60426 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 28 insertions, 5 deletions

diff --git a/chrome/renderer/render_widget.cc b/chrome/renderer/render_widget.cc
index 3252097..f5a7ebe 100644
--- a/chrome/renderer/render_widget.cc
+++ b/chrome/renderer/render_widget.cc
@@ -505,11 +505,24 @@ 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::Id();
+  TransportDIB* dib = NULL;
   std::vector<gfx::Rect> copy_rects;
-  if (!is_gpu_rendering_active_) {
+  gfx::Rect optimized_copy_rect, optimized_copy_location;
+  if (update.scroll_rect.IsEmpty() &&
+      !is_gpu_rendering_active_ &&
+      GetBitmapForOptimizedPluginPaint(bounds, &dib, &optimized_copy_location,
+                                       &optimized_copy_rect)) {
+    bounds = optimized_copy_location;
+    copy_rects.push_back(optimized_copy_rect);
+    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 +551,8 @@ 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 +561,7 @@ 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 +903,15 @@ void RenderWidget::OnSetTextDirection(WebTextDirection direction) {
   webwidget_->setTextDirection(direction);
 }
 
+bool RenderWidget::GetBitmapForOptimizedPluginPaint(
+    const gfx::Rect& paint_bounds,
+    TransportDIB** dib,
+    gfx::Rect* location,
+    gfx::Rect* clip) {
+  // Normal RenderWidgets don't support optimized plugin painting.
+  return false;
+}
+
 void RenderWidget::SetHidden(bool hidden) {
   if (is_hidden_ == hidden)
     return;