Don't copy the Graphics2D when binding a new one. This brings the

ppapi/cpp/paint_manager.h

 // 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.
 
 #ifndef PPAPI_CPP_PAINT_MANAGER_H_
 #define PPAPI_CPP_PAINT_MANAGER_H_
 
 #include <vector>
 
 #include "ppapi/cpp/completion_callback.h"
@@ skipping 128 matching lines @@
   // this will be a NOP. If the size has changed, a new device will be
   // allocated to the given size and a paint to that device will be scheduled.
   //
   // This is intended to be called from ViewChanged with the size of the
   // plugin. Since it tracks the old size and only allocates when the size
   // changes, you can always call this function without worrying about whether
   // the size changed or ViewChanged is called for another reason (like the
   // position changed).
   void SetSize(const Size& new_size);
 
-  // Provides access to the underlying device in case you need it. Note: if
-  // you call Flush on this device the paint manager will get very confused,
-  // don't do this!
+  // Provides access to the underlying device in case you need it. If you have
+  // done a SetSize, note that the graphics context won't be updated until
+  // right before the next OnPaint call.
+  //
+  // Note: if you call Flush on this device the paint manager will get very
+  // confused, don't do this!
   const Graphics2D& graphics() const { return graphics_; }
   Graphics2D& graphics() { return graphics_; }
 
   // Invalidate the entire plugin.
   void Invalidate();
 
   // Invalidate the given rect.
   void InvalidateRect(const Rect& rect);
 
   // The given rect should be scrolled by the given amounts.
   void ScrollRect(const Rect& clip_rect, const Point& amount);
 
+  // Returns the size of the graphics context for the next paint operation.
+  // This is the pending size if a resize is pending (the plugin has called
+  // SetSize but we haven't actually painted it yet), or the current size of
+  // no resize is pending.
+  Size GetEffectiveSize() const;
+
  private:
   // Disallow copy and assign (these are unimplemented).
   PaintManager(const PaintManager&);
   PaintManager& operator=(const PaintManager&);
 
   // Makes sure there is a callback that will trigger a paint at a later time.
   // This will be either a Flush callback telling us we're allowed to generate
   // more data, or, if there's no flush callback pending, a manual call back
   // to the message loop via ExecuteOnMainThread.
   void EnsureCallbackPending();
@@ skipping 19 matching lines @@
 
   // This graphics device will be is_null() if no graphics has been manually
   // set yet.
   Graphics2D graphics_;
 
   PaintAggregator aggregator_;
 
   // See comment for EnsureCallbackPending for more on how these work.
   bool manual_callback_pending_;
   bool flush_pending_;
+
+  // When we get a resize, we don't bind right away (see SetSize). The
+  // has_pending_resize_ tells us that we need to do a resize for the next
+  // paint operation. When true, the new size is in pending_size_.
+  bool has_pending_resize_;
+  Size pending_size_;
 };
 
 }  // namespace pp
 
 #endif  // PPAPI_CPP_PAINT_MANAGER_H_