Get real GPU memory values on NV+Linux and OS X

ui/gl/gl_context_glx.cc

Index: ui/gl/gl_context_glx.cc
diff --git a/ui/gl/gl_context_glx.cc b/ui/gl/gl_context_glx.cc
index d05264485e1a0d70fc015b66b00e218096dc8c33..51c32870a0c471a368ac1272e375ed6bca7ee43b 100644
--- a/ui/gl/gl_context_glx.cc
+++ b/ui/gl/gl_context_glx.cc
@@ -244,6 +244,17 @@ std::string GLContextGLX::GetExtensions() {
   return GLContext::GetExtensions();
 }
 
+bool GLContextGLX::GetTotalGpuMemory(size_t& bytes) {
+  bytes = 0;
+  if (HasExtension("GL_NVX_gpu_memory_info")) {
+    GLint kbytes = 0;
+    glGetIntegerv(GL_GPU_MEMORY_INFO_DEDICATED_VIDMEM_NVX, &kbytes);
+    bytes = 1024*kbytes;
+    return true;
+  }
+  return false;
+}
+
 bool GLContextGLX::WasAllocatedUsingRobustnessExtension() {
   return GLSurfaceGLX::IsCreateContextRobustnessSupported();
 }