TensorFlow: Upstream changes to git.

Changes:
- Correct number of CPUs reported on mac.
- Doc updates.

Base CL: 107355041

navbar.md

@@ -0,0 +1,11 @@
+# TensorFlow
+
+* [Home][home]
+* [Getting Started](/tensorflow/g3doc/get_started/index.md)
+* [Mechanics](/tensorflow/g3doc/how_tos/index.md)
+* [Tutorials](/tensorflow/g3doc/tutorials/index.md)
+* [Python API](/tensorflow/g3doc/api_docs/python/index.md)
+* [C++ API](/tensorflow/g3doc/api_docs/cc/index.md)
+* [Other Resources](/tensorflow/g3doc/resources/index.md)
+
+[home]: /tensorflow/g3doc/index.md

tensorflow/core/platform/posix/port.cc

@@ -9,6 +9,9 @@
 #ifdef SNAPPY
 #include <snappy.h>
 #endif
+#if defined(__APPLE__) && defined(__MACH__)
+#include <thread>
+#endif
 
 namespace tensorflow {
 namespace port {
@@ -29,6 +32,9 @@ int NumSchedulableCPUs() {
     return CPU_COUNT(&cpuset);
   }
   perror("sched_getaffinity");
+#endif
+#if defined(__APPLE__) && defined(__MACH__)
+  return std::thread::hardware_concurrency();
 #endif
   const int kDefaultCores = 4;  // Semi-conservative guess
   fprintf(stderr, "can't determine number of CPU cores: assuming %d\n",