Two tweaks for accelerated painting:

views/view.cc

 // Copyright (c) 2011 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 "views/view.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 395 matching lines @@
       return;
     transform_.reset(NULL);
 #if !defined(COMPOSITOR_2)
     canvas_.reset();
 #else
     texture_.reset();
 #endif
     SchedulePaint();
   } else {
     transform_.reset(new ui::Transform(transform));
-    // TODO: this needs to trigger a paint on the widget. It shouldn't use
-    // SchedulePaint as we don't want to mark the views dirty.
+    if (!texture_.get()) {

[Ben Goodger (Google), 2011/05/20 18:10:02]

don't you need this to be #if defined(COMPOSITOR_2)?

+      // We don't yet have a texture. SchedulePaint so one is created.
+      SchedulePaint();
+    } else {
+      // We have a texture. When the transform changes and the texture is up to
+      // date we don't want to SchedulePaint as it'll trigger painting to the
+      // texture. Instead we tell the Widget to paint, which makes the
+      // compositor draw using the existing texture.
+      // We schedule paint the complete bounds as compositor generally don't
+      // support partial painting.
+      Widget* widget = GetWidget();
+      if (widget)
+        widget->SchedulePaintInRect(widget->GetRootView()->bounds());
+    }
   }
 }
 
 // RTL positioning -------------------------------------------------------------
 
 gfx::Rect View::GetMirroredBounds() const {
   gfx::Rect bounds(bounds_);
   bounds.set_x(GetMirroredX());
   return bounds;
 }
@@ skipping 734 matching lines @@
 
   for (int i = 0, count = child_count(); i < count; ++i)
     GetChildViewAt(i)->PaintComposite();
 }
 
 void View::PaintToTexture(const gfx::Rect& dirty_region) {
   if (!IsVisible())
     return;
 
   if (ShouldPaintToTexture() && texture_needs_updating_) {
-    texture_clip_rect_ = dirty_region;
-    Paint(NULL);
-    texture_clip_rect_.SetRect(0, 0, 0, 0);
+    if (!texture_.get()) {

[Ben Goodger (Google), 2011/05/20 18:10:02]

again with the ifdefs

+      // If we have no texture paint the whole view. We do this to handle two
+      // cases:
+      // . Workaround for WidgetWin/WindowWin. In particular its possible to
+      //   create the rootview at the non-client size, even though we'll never
+      //   paint at that size.
+      // . In case the texture is recreated and a partial paint was scheduled.
+      Paint(NULL);
+    } else {
+      texture_clip_rect_ = dirty_region;
+      Paint(NULL);
+      texture_clip_rect_.SetRect(0, 0, 0, 0);
+    }
   } else {
     // Forward to all children as a descendant may be dirty and have a texture.
     for (int i = child_count() - 1; i >= 0; --i) {
       View* child_view = GetChildViewAt(i);
       gfx::Rect child_dirty_rect(child_view->bounds().Intersect(dirty_region));
       if (!child_dirty_rect.IsEmpty()) {
         child_dirty_rect.Offset(-child_view->x(), -child_view->y());
         GetChildViewAt(i)->PaintToTexture(child_dirty_rect);
       }
     }
@@ skipping 666 matching lines @@
     result.append(GetChildViewAt(i)->PrintViewGraph(false));
 
   if (first)
     result.append("}\n");
 
   return result;
 }
 #endif
 
 }  // namespace views