Add compositor support for half-float RGBA buffers and textures

cc/output/gl_renderer.h

 // Copyright 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 CC_OUTPUT_GL_RENDERER_H_
 #define CC_OUTPUT_GL_RENDERER_H_
 
 #include <deque>
 #include <vector>
 
@@ skipping 67 matching lines @@
                              const gfx::Rect& device_rect);
   void ReleaseRenderPassTextures();
   enum BoundGeometry { NO_BINDING, SHARED_BINDING, CLIPPED_BINDING };
   void PrepareGeometry(BoundGeometry geometry_to_bind);
   void SetStencilEnabled(bool enabled);
   bool stencil_enabled() const { return stencil_shadow_; }
   void SetBlendEnabled(bool enabled);
   bool blend_enabled() const { return blend_shadow_; }
 
   bool CanPartialSwap() override;
+  ResourceFormat BackbufferFormat() const override;
   void BindFramebufferToOutputSurface(DrawingFrame* frame) override;
   bool BindFramebufferToTexture(DrawingFrame* frame,
                                 const ScopedResource* resource) 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 class DrawQuad*,
                   const gfx::QuadF* draw_region) override;
@@ skipping 272 matching lines @@
   gfx::Size offscreen_stencil_renderbuffer_size_;
 
   base::WeakPtrFactory<GLRenderer> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(GLRenderer);
 };
 
 }  // namespace cc
 
 #endif  // CC_OUTPUT_GL_RENDERER_H_