Added variable name as required by style guide.

gpu/demos/hello_triangle/main.cc

Index: gpu/demos/hello_triangle/main.cc
===================================================================
--- gpu/demos/hello_triangle/main.cc	(revision 36357)
+++ gpu/demos/hello_triangle/main.cc	(working copy)
@@ -19,7 +19,7 @@
   bool Init();
 
  protected:
-  virtual void Draw(float);
+  virtual void Draw(float elapsed_sec);
 
  private:
   ESContext context_;
@@ -49,7 +49,7 @@
   return true;
 }
 
-void HelloTriangle::Draw(float) {
+void HelloTriangle::Draw(float /*elapsed_sec*/) {
   htDraw(&context_);
 }
 }  // namespace gpu_demos