Adding support for per vertex opacity on textured layer

cc/gl_renderer_draw_cache.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_GL_RENDERER_DRAW_CACHE_H_
 #define CC_GL_RENDERER_DRAW_CACHE_H_
 
 #include <vector>
 
 
 // Collects 4 floats at a time for easy upload to GL.
 struct Float4 { float data[4]; };
 
 // Collects 16 floats at a time for easy upload to GL.
 struct Float16 { float data[16]; };
 
 // A cache for storing textured quads to be drawn.  Stores the minimum required
 // data to tell if two back to back draws only differ in their transform. Quads
 // that only differ by transform may be coalesced into a single draw call.
 struct TexturedQuadDrawCache {
   TexturedQuadDrawCache();
   ~TexturedQuadDrawCache();
 
   // Values tracked to determine if textured quads may be coalesced.
   int program_id;
   int resource_id;
-  float alpha;
   bool use_premultiplied_alpha;
   bool needs_blending;
 
   // Information about the program binding that is required to draw.
-  int alpha_location;
   int uv_xform_location;
+  int vertex_opacity_location;
   int matrix_location;
 
   // A cache for the coalesced quad data.
   std::vector<Float4> uv_xform_data;
+  std::vector<float> vertex_opacity_data;
   std::vector<Float16> matrix_data;
 };
 
 #endif // CC_GL_RENDERER_DRAW_CACHE_H_