Implemented failIfMajorPerformanceCaveat WebGL context creation attribute.

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 2b792130c00fe8cfa55c2bff58e1790879ceacc6..c121fa2fc507a97616cf44d2984ed440a3e91c88 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -2215,6 +2215,19 @@ bool GLES2DecoderImpl::Initialize(
   context_ = context;
   surface_ = surface;
 
+  ContextCreationAttribHelper attrib_parser;
+  if (!attrib_parser.Parse(attribs))
+    return false;
+
+  // If the failIfMajorPerformanceCaveat context creation attribute was true
+  // and we are using a software renderer, fail.
+  if (attrib_parser.fail_if_major_perf_caveat_ &&
+      feature_info_->feature_flags().is_swiftshader) {
+    group_ = NULL;  // Must not destroy ContextGroup if it is not initialized.
+    Destroy(true);
+    return false;
+  }
+
   if (!group_->Initialize(this, disallowed_features)) {
     LOG(ERROR) << "GpuScheduler::InitializeCommon failed because group "
                << "failed to initialize.";
@@ -2277,10 +2290,6 @@ bool GLES2DecoderImpl::Initialize(
   glActiveTexture(GL_TEXTURE0);
   CHECK_GL_ERROR();
 
-  ContextCreationAttribHelper attrib_parser;
-  if (!attrib_parser.Parse(attribs))
-    return false;
-
   if (offscreen) {
     if (attrib_parser.samples_ > 0 && attrib_parser.sample_buffers_ > 0 &&
         features().chromium_framebuffer_multisample) {