Fix PRIMITIVE_RESTART_FIXED_INDEX handling in command buffer and WebGL 2.0.

gpu/command_buffer/service/gles2_cmd_decoder.cc

Index: gpu/command_buffer/service/gles2_cmd_decoder.cc
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.cc b/gpu/command_buffer/service/gles2_cmd_decoder.cc
index 5e1ec96deb2db0e2627a09fcd24820b653c90b71..57a7ddac863599656377fb2e1e0bc5f0327b1e8b 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -8282,7 +8282,9 @@ error::Error GLES2DecoderImpl::DoDrawElements(const char* function_name,
       state_.vertex_attrib_manager->element_array_buffer();
 
   if (!element_array_buffer->GetMaxValueForRange(
-      offset, count, type, &max_vertex_accessed)) {
+          offset, count, type,
+          state_.GetEnabled(GL_PRIMITIVE_RESTART_FIXED_INDEX),

[piman, 2016/03/19 00:56:11]

nit: state_.enable_flags.primitive_restart_fixed_index, saves a switch.

[Ken Russell (switch to Gerrit), 2016/03/19 04:06:53]

Done here and below.

+          &max_vertex_accessed)) {
     LOCAL_SET_GL_ERROR(
         GL_INVALID_OPERATION, function_name, "range out of bounds for buffer");
     return error::kNoError;
@@ -8380,7 +8382,9 @@ GLuint GLES2DecoderImpl::DoGetMaxValueInBufferCHROMIUM(
         GL_INVALID_VALUE, "GetMaxValueInBufferCHROMIUM", "unknown buffer");
   } else {
     if (!buffer->GetMaxValueForRange(
-        offset, count, type, &max_vertex_accessed)) {
+            offset, count, type,
+            state_.GetEnabled(GL_PRIMITIVE_RESTART_FIXED_INDEX),

[piman, 2016/03/19 00:56:11]

This is used by the client side, for client-side buffers. We're kind of baking
in the behavior of the client side, that only calls this before drawing - so
this state is set. Worth at least a comment. Otherwise, the slightly cleaner way
is to pass this bit from the client side, so that it can describe how it wants
to interpret the buffer values.

[Ken Russell (switch to Gerrit), 2016/03/19 04:06:53]

Added a comment about how this value is used and why the current code is
correct.

+            &max_vertex_accessed)) {
       // TODO(gman): Should this be a GL error or a command buffer error?
       LOCAL_SET_GL_ERROR(
           GL_INVALID_OPERATION,