cc: Remove the software compositing bool from PrepareTextureMailbox

cc/output/renderer_capabilities_impl.h

 // Copyright 2012 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_OUTPUT_RENDERER_CAPABILITIES_IMPL_H_
 #define CC_OUTPUT_RENDERER_CAPABILITIES_IMPL_H_
 
 #include "cc/output/renderer_capabilities.h"
 
 namespace cc {
 
 struct RendererCapabilitiesImpl {
   RendererCapabilitiesImpl();
   ~RendererCapabilitiesImpl();
 
   // Capabilities copied to main thread.
   ResourceFormat best_texture_format = RGBA_8888;
   int max_texture_size = 0;
-  bool using_shared_memory_resources = false;
 
-  RendererCapabilities MainThreadCapabilities() const;
+  RendererCapabilities MainThreadCapabilities() const {
+    return RendererCapabilities(best_texture_format, max_texture_size);
+  }
 };
 
 }  // namespace cc
 
 #endif  // CC_OUTPUT_RENDERER_CAPABILITIES_IMPL_H_