Don't unnecessarily paint pixles when doing optimized always-on-top pepper pa...

chrome/renderer/render_widget.cc

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/renderer/render_widget.h"
 
 #include "app/surface/transport_dib.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/message_loop.h"
@@ skipping 423 matching lines @@
     // painting, because that avoids copying the plugin image to a different
     // paint rect. Unfortunately, if anything on the page is animating other
     // than the movie, it break this optimization since the union of the
     // invalid regions will be larger than the plugin.
     //
     // This code optimizes that case, where we can still avoid painting in
     // WebKit and filling the background (which can be slow) and just painting
     // the plugin. Unlike the DoDeferredUpdate case, an extra copy is still
     // required.
     optimized_instance->Paint(webkit_glue::ToWebCanvas(canvas),
-                              optimized_copy_location, optimized_copy_location);
+                              optimized_copy_location, rect);
   } else {
     // Normal painting case.
     webwidget_->paint(webkit_glue::ToWebCanvas(canvas), rect);
 
     // Flush to underlying bitmap.  TODO(darin): is this needed?
     canvas->getTopPlatformDevice().accessBitmap(false);
   }
 
   PaintDebugBorder(rect, canvas);
   canvas->restore();
@@ skipping 68 matching lines @@
   // within the plugin. There is a related optimization in PaintRect for the
   // case where there may be multiple invalid regions.
   TransportDIB::Id dib_id = TransportDIB::Id();
   TransportDIB* dib = NULL;
   std::vector<gfx::Rect> copy_rects;
   gfx::Rect optimized_copy_rect, optimized_copy_location;
   if (update.scroll_rect.IsEmpty() &&
       !is_accelerated_compositing_active_ &&
       GetBitmapForOptimizedPluginPaint(bounds, &dib, &optimized_copy_location,
                                        &optimized_copy_rect)) {
+    // Only update the part of the plugin that actually changed.
+    optimized_copy_rect = optimized_copy_rect.Intersect(bounds);
     bounds = optimized_copy_location;
     copy_rects.push_back(optimized_copy_rect);
     dib_id = dib->id();
   } else if (!is_accelerated_compositing_active_) {
     // Compute a buffer for painting and cache it.
     scoped_ptr<skia::PlatformCanvas> canvas(
         RenderProcess::current()->GetDrawingCanvas(&current_paint_buf_,
                                                    bounds));
     if (!canvas.get()) {
       NOTREACHED();
@@ skipping 478 matching lines @@
 
 void RenderWidget::CleanupWindowInPluginMoves(gfx::PluginWindowHandle window) {
   for (WebPluginGeometryVector::iterator i = plugin_window_moves_.begin();
        i != plugin_window_moves_.end(); ++i) {
     if (i->window == window) {
       plugin_window_moves_.erase(i);
       break;
     }
   }
 }