cc: Fix vertex opacity shaders

cc/output/shader.cc

 // Copyright 2011 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.
 
 #include "cc/output/shader.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <vector>
@@ skipping 355 matching lines @@
     } else {
       SRC("v_texCoord = texCoord;");
     }
   }
 
   // Write varying vertex opacity.
   if (has_vertex_opacity_) {
     DCHECK(use_uniform_arrays_);
     HDR("uniform float opacity[NUM_QUADS * 4];");
     HDR("varying float v_alpha;");
-    SRC("v_alpha = opacity[quad_index];");
+    SRC("v_alpha = opacity[vertex_index];");
   }
 
   // Add cargo-culted dummy variables for Android.
   if (has_dummy_variables_) {
     HDR("uniform TexCoordPrecision vec2 dummy_uniform;");
     HDR("varying TexCoordPrecision vec2 dummy_varying;");
     SRC("dummy_varying = dummy_uniform;");
   }
 
   source += "}\n";
@@ skipping 617 matching lines @@
       else
         SRC("gl_FragColor = ApplyBlendMode(texColor, 0.0);");
       break;
   }
   source += "}\n";
 
   return header + source;
 }
 
 }  // namespace cc