SimpleFileTracker: out-of-line some shared histogram code.

This is apparently a good practice since these macros can generate
quite a bit of code, which I didn't know at the time of writing this.

Change-Id: If28af80c07200562f029e2c588ffc5666a5e8326
Reviewed-on: https://chromium-review.googlesource.com/c/1459579Reviewed-by: Eric Orth <ericorth@chromium.org>
Commit-Queue: Maks Orlovich <morlovich@chromium.org>
Cr-Commit-Position: refs/heads/master@{#630117}

net/disk_cache/simple/simple_file_tracker.cc

@@ -17,6 +17,15 @@
 
 namespace disk_cache {
 
+namespace {
+
+void RecordFileDescripterLimiterOp(FileDescriptorLimiterOp op) {
+  UMA_HISTOGRAM_ENUMERATION("SimpleCache.FileDescriptorLimiterAction", op,
+                            FD_LIMIT_OP_MAX);
+}
+
+}  // namespace
+
 SimpleFileTracker::SimpleFileTracker(int file_limit)
     : file_limit_(file_limit) {}
 
@@ -252,8 +261,7 @@ void SimpleFileTracker::CloseFilesIfTooManyOpen(
           tracked_files->files[j] != nullptr) {
         files_to_close->push_back(std::move(tracked_files->files[j]));
         --open_files_;
-        UMA_HISTOGRAM_ENUMERATION("SimpleCache.FileDescriptorLimiterAction",
-                                  FD_LIMIT_CLOSE_FILE, FD_LIMIT_OP_MAX);
+        RecordFileDescripterLimiterOp(FD_LIMIT_CLOSE_FILE);
       }
     }
 
@@ -283,14 +291,12 @@ void SimpleFileTracker::ReopenFile(TrackedFiles* owners_files,
   owners_files->files[file_index] =
       std::make_unique<base::File>(file_path, flags);
   if (owners_files->files[file_index]->IsValid()) {
-    UMA_HISTOGRAM_ENUMERATION("SimpleCache.FileDescriptorLimiterAction",
-                              FD_LIMIT_REOPEN_FILE, FD_LIMIT_OP_MAX);
+    RecordFileDescripterLimiterOp(FD_LIMIT_REOPEN_FILE);
 
     ++open_files_;
   } else {
     owners_files->files[file_index] = nullptr;
-    UMA_HISTOGRAM_ENUMERATION("SimpleCache.FileDescriptorLimiterAction",
-                              FD_LIMIT_FAIL_REOPEN_FILE, FD_LIMIT_OP_MAX);
+    RecordFileDescripterLimiterOp(FD_LIMIT_FAIL_REOPEN_FILE);
   }
 }