Rewrite std::string("") to std::string(), Linux edition.

content/gpu/gpu_info_collector.cc

Index: content/gpu/gpu_info_collector.cc
diff --git a/content/gpu/gpu_info_collector.cc b/content/gpu/gpu_info_collector.cc
index 86fb0c57c08c36172c43f2eac428f3afb46e6224..d3f5867b770e28d8421bb8a5ada0db9bf3d19e56 100644
--- a/content/gpu/gpu_info_collector.cc
+++ b/content/gpu/gpu_info_collector.cc
@@ -53,7 +53,7 @@ std::string GetGLString(unsigned int pname) {
       reinterpret_cast<const char*>(glGetString(pname));
   if (gl_string)
     return std::string(gl_string);
-  return "";
+  return std::string();
 }
 
 // Return a version string in the format of "major.minor".
@@ -71,7 +71,7 @@ std::string GetVersionFromString(const std::string& version_string) {
     if (pieces.size() >= 2)
       return pieces[0] + "." + pieces[1];
   }
-  return "";
+  return std::string();
 }
 
 }  // namespace anonymous