cc: Don't discard framebuffer when using partial swaps

cc/debug/test_web_graphics_context_3d.h

 // Copyright 2013 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 CC_DEBUG_TEST_WEB_GRAPHICS_CONTEXT_3D_H_
 #define CC_DEBUG_TEST_WEB_GRAPHICS_CONTEXT_3D_H_
 
 #include <vector>
 
 #include "base/compiler_specific.h"
@@ skipping 172 matching lines @@
   }
   void set_have_extension_io_surface(bool have) {
     test_capabilities_.iosurface = have;
   }
   void set_have_extension_egl_image(bool have) {
     test_capabilities_.egl_image_external = have;
   }
   void set_have_post_sub_buffer(bool have) {
     test_capabilities_.post_sub_buffer = have;
   }
+  void set_have_discard_framebuffer(bool have) {
+    test_capabilities_.discard_framebuffer = have;
+  }
 
   // When this context is lost, all contexts in its share group are also lost.
   void add_share_group_context(WebKit::WebGraphicsContext3D* context3d) {
     shared_contexts_.push_back(context3d);
   }
 
   void set_max_texture_size(int size) { max_texture_size_ = size; }
 
   static const WebKit::WebGLId kExternalTextureId;
   virtual WebKit::WebGLId NextTextureId();
@@ skipping 77 matching lines @@
 
   scoped_refptr<Namespace> namespace_;
   static Namespace* shared_namespace_;
 
   base::WeakPtrFactory<TestWebGraphicsContext3D> weak_ptr_factory_;
 };
 
 }  // namespace cc
 
 #endif  // CC_DEBUG_TEST_WEB_GRAPHICS_CONTEXT_3D_H_