Empty program info log should not be a '\0' string in WebGL

gpu/command_buffer/service/program_manager.cc

 // Copyright (c) 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.
 
 #include "gpu/command_buffer/service/program_manager.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 464 matching lines @@
       output += hashed_name;
   }
 
   return output + input.as_string();
 }
 
 void Program::UpdateLogInfo() {
   GLint max_len = 0;
   glGetProgramiv(service_id_, GL_INFO_LOG_LENGTH, &max_len);
   if (max_len == 0) {
-    set_log_info(NULL);
+    set_log_info(nullptr);
     return;
   }
   std::unique_ptr<char[]> temp(new char[max_len]);
   GLint len = 0;
   glGetProgramInfoLog(service_id_, max_len, &len, temp.get());
   DCHECK(max_len == 0 || len < max_len);
   DCHECK(len == 0 || temp[len] == '\0');
   std::string log(temp.get(), len);
-  set_log_info(ProcessLogInfo(log).c_str());
+  log = ProcessLogInfo(log);
+  set_log_info(log.empty() ? nullptr : log.c_str());
 }
 
 void Program::ClearUniforms(std::vector<uint8_t>* zero_buffer) {
   DCHECK(zero_buffer);
   if (uniforms_cleared_) {
     return;
   }
   uniforms_cleared_ = true;
   for (const UniformInfo& uniform_info : uniform_infos_) {
     GLint location = uniform_info.element_locations[0];
@@ skipping 2059 matching lines @@
   DCHECK(program);
   program->ClearUniforms(&zero_);
 }
 
 int32_t ProgramManager::MakeFakeLocation(int32_t index, int32_t element) {
   return index + element * 0x10000;
 }
 
 }  // namespace gles2
 }  // namespace gpu