Add ES3 commands GetVertexAttribI{u}iv to GPU command buffer.

gpu/command_buffer/service/context_state.h

Index: gpu/command_buffer/service/context_state.h
diff --git a/gpu/command_buffer/service/context_state.h b/gpu/command_buffer/service/context_state.h
index 32bef4cea3ec3f9099eb087b40090f22f2ec41bb..a4a8eda250d4e105f46e9ca7ed1e716a2d12d654 100644
--- a/gpu/command_buffer/service/context_state.h
+++ b/gpu/command_buffer/service/context_state.h
@@ -102,13 +102,23 @@ struct GPU_EXPORT TextureUnit {
 };
 
 struct Vec4 {
+  enum DataType {
+    kFloat,
+    kInt,
+    kUInt,
+  };
+
   Vec4() {
     v[0] = 0.0f;
     v[1] = 0.0f;
     v[2] = 0.0f;
     v[3] = 1.0f;
+    type = kFloat;
   }
+  // Use double type here so when storing data of type GLfloat, GLint,
+  // or GLuint, there will be no data loss.
   float v[4];
+  DataType type;

[Zhenyao Mo, 2015/05/12 23:57:45]

Note that in this CL, we don't hook up the setting of this |type| field with any
of the glVertexAttrib* calls.  This CL limits to the glGetVertexAttrib handling.
 An followup CL will fix such issues.

 };
 
 struct GPU_EXPORT ContextState {