Fix partial updates of transparent plugin backgrounds on Mac

chrome/plugin/webplugin_proxy.cc

 // Copyright (c) 2009 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/plugin/webplugin_proxy.h"
 
 #include "build/build_config.h"
 
 #include "app/gfx/canvas.h"
 #if defined(OS_WIN)
@@ skipping 404 matching lines @@
   windowless_canvas_->restore();
 #elif defined(OS_MACOSX)
   CGContextSaveGState(windowless_context_);
   if (!background_context_.get()) {
     CGContextSetFillColorWithColor(windowless_context_,
                                    CGColorGetConstantColor(kCGColorBlack));
     CGContextFillRect(windowless_context_, rect.ToCGRect());
   } else {
     scoped_cftyperef<CGImageRef> image(
         CGBitmapContextCreateImage(background_context_));
+    CGRect source_rect = rect.ToCGRect();
+    // Flip the rect we use to pull from the canvas, since it's upside-down.
+    source_rect.origin.y = CGImageGetHeight(image) - rect.y() - rect.height();
     scoped_cftyperef<CGImageRef> sub_image(
-        CGImageCreateWithImageInRect(image, rect.ToCGRect()));
+        CGImageCreateWithImageInRect(image, source_rect));
     CGContextDrawImage(windowless_context_, rect.ToCGRect(), sub_image);
   }
   CGContextClipToRect(windowless_context_, rect.ToCGRect());
   delegate_->Paint(windowless_context_, rect);
   CGContextRestoreGState(windowless_context_);
 #endif
 }
 
 void WebPluginProxy::UpdateGeometry(
     const gfx::Rect& window_rect,
@@ skipping 149 matching lines @@
   while (index != resource_clients_.end()) {
     WebPluginResourceClient* client = (*index).second;
 
     if (client == resource_client) {
       resource_clients_.erase(index++);
     } else {
       index++;
     }
   }
 }