Rename WTF::{Arena|Tree}TestHelpers namepsace to WTF::{arena|tree}_test_helpers

https://google.github.io/styleguide/cppguide.html#Namespace_Names
> Namespace names are all lower-case.

This CL has no behavior changes.

Bug: 889726
Change-Id: I9dc96c9669ca28719ecda9d571eec0311d014a82
Reviewed-on: https://chromium-review.googlesource.com/c/1329711Reviewed-by: Kent Tamura <tkent@chromium.org>
Commit-Queue: Zhuoyu Qian <zhuoyu.qian@samsung.com>
Cr-Commit-Position: refs/heads/master@{#607150}

third_party/blink/renderer/platform/wtf/pod_arena_test.cc

@@ -32,7 +32,7 @@
 
 namespace WTF {
 
-using ArenaTestHelpers::TrackedAllocator;
+using arena_test_helpers::TrackedAllocator;
 
 namespace {
 

third_party/blink/renderer/platform/wtf/pod_arena_test_helpers.h

@@ -33,7 +33,7 @@
 #include <gtest/gtest.h>
 
 namespace WTF {
-namespace ArenaTestHelpers {
+namespace arena_test_helpers {
 
 // An allocator for the PODArena which tracks the regions which have
 // been allocated.
@@ -65,7 +65,7 @@ class TrackedAllocator final : public PODArena::FastMallocAllocator {
   Vector<void*> allocated_regions_;
 };
 
-}  // namespace ArenaTestHelpers
+}  // namespace arena_test_helpers
 }  // namespace WTF
 
 #endif  // THIRD_PARTY_BLINK_RENDERER_PLATFORM_WTF_POD_ARENA_TEST_HELPERS_H_

third_party/blink/renderer/platform/wtf/pod_free_list_arena_test.cc

@@ -32,7 +32,7 @@
 
 namespace WTF {
 
-using ArenaTestHelpers::TrackedAllocator;
+using arena_test_helpers::TrackedAllocator;
 
 namespace {
 

third_party/blink/renderer/platform/wtf/pod_interval_tree_test.cc

@@ -34,8 +34,8 @@
 
 namespace WTF {
 
-using TreeTestHelpers::InitRandom;
-using TreeTestHelpers::NextRandom;
+using tree_test_helpers::InitRandom;
+using tree_test_helpers::NextRandom;
 
 #ifndef NDEBUG
 template <>

third_party/blink/renderer/platform/wtf/pod_red_black_tree_test.cc

@@ -34,9 +34,9 @@
 
 namespace WTF {
 
-using ArenaTestHelpers::TrackedAllocator;
-using TreeTestHelpers::InitRandom;
-using TreeTestHelpers::NextRandom;
+using arena_test_helpers::TrackedAllocator;
+using tree_test_helpers::InitRandom;
+using tree_test_helpers::NextRandom;
 
 TEST(PODRedBlackTreeTest, TestTreeAllocatesFromArena) {
   scoped_refptr<TrackedAllocator> allocator = TrackedAllocator::Create();

third_party/blink/renderer/platform/wtf/pod_tree_test_helpers.cc

@@ -28,7 +28,7 @@
 #include <cstdlib>
 
 namespace WTF {
-namespace TreeTestHelpers {
+namespace tree_test_helpers {
 
 void InitRandom(const int32_t seed) {
   srand(seed);
@@ -39,5 +39,5 @@ int32_t NextRandom(const int32_t maximum_value) {
   return rand() % maximum_value;
 }
 
-}  // namespace TreeTestHelpers
+}  // namespace tree_test_helpers
 }  // namespace WTF

third_party/blink/renderer/platform/wtf/pod_tree_test_helpers.h

@@ -34,7 +34,7 @@
 #include <stdint.h>
 
 namespace WTF {
-namespace TreeTestHelpers {
+namespace tree_test_helpers {
 
 // Initializes the pseudo-random number generator with a specific seed.
 void InitRandom(const int32_t seed);
@@ -44,7 +44,7 @@ void InitRandom(const int32_t seed);
 // produce undefined results.
 int32_t NextRandom(const int32_t maximum_value);
 
-}  // namespace TreeTestHelpers
+}  // namespace tree_test_helpers
 }  // namespace WTF
 
 #endif  // THIRD_PARTY_BLINK_RENDERER_PLATFORM_WTF_POD_TREE_TEST_HELPERS_H_