Fix build_ios.sh bug (#194) due to name collision.

Summary: Closes https://github.com/caffe2/caffe2/pull/200

Differential Revision: D4704479

Pulled By: Yangqing

fbshipit-source-id: 7a618fa2cd57fd2ead5cede5d5aed033284ea67e
diff --git a/caffe2/image/image_input_op.h b/caffe2/image/image_input_op.h
index d9b26de..fe42344 100644
--- a/caffe2/image/image_input_op.h
+++ b/caffe2/image/image_input_op.h
@@ -62,7 +62,7 @@
 
   // thread pool for parse + decode
   int num_decode_threads_;
-  std::shared_ptr<ThreadPool> thread_pool_;
+  std::shared_ptr<TaskThreadPool> thread_pool_;
 };
 
 
@@ -86,7 +86,7 @@
               "use_gpu_transform", 0)),
         num_decode_threads_(OperatorBase::template GetSingleArgument<int>(
               "decode_threads", 4)),
-        thread_pool_(new ThreadPool(num_decode_threads_))
+        thread_pool_(new TaskThreadPool(num_decode_threads_))
 {
   if (operator_def.input_size() == 0) {
     LOG(ERROR) << "You are using an old ImageInputOp format that creates "
diff --git a/caffe2/utils/thread_pool.h b/caffe2/utils/thread_pool.h
index 5ff636b..af7180d 100644
--- a/caffe2/utils/thread_pool.h
+++ b/caffe2/utils/thread_pool.h
@@ -7,7 +7,7 @@
 #include <queue>
 #include <thread>
 
-class ThreadPool{
+class TaskThreadPool{
  private:
     std::queue< std::function< void() > > tasks_;
     std::vector<std::thread> threads_;
@@ -21,17 +21,17 @@
 
  public:
     /// @brief Constructor.
-    explicit ThreadPool(std::size_t pool_size)
+    explicit TaskThreadPool(std::size_t pool_size)
         :  threads_(pool_size), running_(true), complete_(true),
            available_(pool_size), total_(pool_size) {
         for ( std::size_t i = 0; i < pool_size; ++i ) {
             threads_[i] = std::thread(
-                std::bind(&ThreadPool::main_loop, this));
+                std::bind(&TaskThreadPool::main_loop, this));
         }
     }
 
     /// @brief Destructor.
-    ~ThreadPool() {
+    ~TaskThreadPool() {
         // Set running flag to false then notify all threads.
         {
             std::unique_lock< std::mutex > lock(mutex_);