Add compositor support for half-float RGBA buffers and textures

cc/output/software_renderer.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_SOFTWARE_RENDERER_H_
 #define CC_OUTPUT_SOFTWARE_RENDERER_H_
 
 #include "base/macros.h"
 #include "cc/base/cc_export.h"
 #include "cc/output/direct_renderer.h"
@@ skipping 19 matching lines @@
   ~SoftwareRenderer() override;
 
   void SwapBuffers(std::vector<ui::LatencyInfo> latency_info) override;
 
   void SetDisablePictureQuadImageFiltering(bool disable) {
     disable_picture_quad_image_filtering_ = disable;
   }
 
  protected:
   bool CanPartialSwap() override;
+  ResourceFormat BackbufferFormat() const override;
   void BindFramebufferToOutputSurface(DrawingFrame* frame) override;
   bool BindFramebufferToTexture(DrawingFrame* frame,
                                 const ScopedResource* texture) override;
   void SetScissorTestRect(const gfx::Rect& scissor_rect) override;
   void PrepareSurfaceForPass(DrawingFrame* frame,
                              SurfaceInitializationMode initialization_mode,
                              const gfx::Rect& render_pass_scissor) override;
   void DoDrawQuad(DrawingFrame* frame,
                   const DrawQuad* quad,
                   const gfx::QuadF* draw_region) override;
@@ skipping 58 matching lines @@
   std::unique_ptr<ResourceProvider::ScopedWriteLockSoftware>
       current_framebuffer_lock_;
   std::unique_ptr<SkCanvas> current_framebuffer_canvas_;
 
   DISALLOW_COPY_AND_ASSIGN(SoftwareRenderer);
 };
 
 }  // namespace cc
 
 #endif  // CC_OUTPUT_SOFTWARE_RENDERER_H_