Store StringId in array instead of map

src/trace_processor/importers/proto/chrome_string_lookup.cc

diff --git a/src/trace_processor/importers/proto/chrome_string_lookup.cc b/src/trace_processor/importers/proto/chrome_string_lookup.cc
index 9a4e11d..dc39a31 100644
--- a/src/trace_processor/importers/proto/chrome_string_lookup.cc
+++ b/src/trace_processor/importers/proto/chrome_string_lookup.cc
@@ -247,38 +247,42 @@
 ChromeStringLookup::ChromeStringLookup(
     TraceStorage* storage,
     bool ignore_predefined_names_for_testing) {
-  for (int32_t i = chrome_enums::ProcessType_MIN;
-       i <= chrome_enums::ProcessType_MAX; ++i) {
+  for (int32_t type = kProcessTypeMin; type <= kProcessTypeMax; ++type) {
     const char* name =
-        GetProcessNameString(i, ignore_predefined_names_for_testing);
-    chrome_process_name_ids_[i] =
+        GetProcessNameString(type, ignore_predefined_names_for_testing);
+    const auto idx = static_cast<size_t>(type - kProcessTypeMin);
+    chrome_process_name_ids_[idx] =
         name ? storage->InternString(name) : kNullStringId;
   }
 
-  for (int32_t i = chrome_enums::ThreadType_MIN;
-       i <= chrome_enums::ThreadType_MAX; ++i) {
+  for (int32_t type = kThreadTypeMin; type <= kThreadTypeMax; ++type) {
     const char* name =
-        GetThreadNameString(i, ignore_predefined_names_for_testing);
-    chrome_thread_name_ids_[i] =
+        GetThreadNameString(type, ignore_predefined_names_for_testing);
+    const auto idx = static_cast<size_t>(type - kThreadTypeMin);
+    chrome_thread_name_ids_[idx] =
         name ? storage->InternString(name) : kNullStringId;
   }
 }
 
 StringId ChromeStringLookup::GetProcessName(int32_t process_type) const {
-  auto process_name_it = chrome_process_name_ids_.find(process_type);
-  if (process_name_it != chrome_process_name_ids_.end())
-    return process_name_it->second;
-
+  if (process_type >= kProcessTypeMin) {
+    const auto idx = static_cast<size_t>(process_type - kProcessTypeMin);
+    if (idx < chrome_process_name_ids_.size()) {
+      return chrome_process_name_ids_[idx];
+    }
+  }
   PERFETTO_DLOG("GetProcessName error: Unknown Chrome process type %u",
                 process_type);
   return kNullStringId;
 }
 
 StringId ChromeStringLookup::GetThreadName(int32_t thread_type) const {
-  auto thread_name_it = chrome_thread_name_ids_.find(thread_type);
-  if (thread_name_it != chrome_thread_name_ids_.end())
-    return thread_name_it->second;
-
+  if (thread_type >= kThreadTypeMin) {
+    const auto idx = static_cast<size_t>(thread_type - kThreadTypeMin);
+    if (idx < chrome_thread_name_ids_.size()) {
+      return chrome_thread_name_ids_[idx];
+    }
+  }
   PERFETTO_DLOG("GetThreadName error: Unknown Chrome thread type %u",
                 thread_type);
   return kNullStringId;

src/trace_processor/importers/proto/chrome_string_lookup.h

diff --git a/src/trace_processor/importers/proto/chrome_string_lookup.h b/src/trace_processor/importers/proto/chrome_string_lookup.h
index e4ed3fb..881ba21 100644
--- a/src/trace_processor/importers/proto/chrome_string_lookup.h
+++ b/src/trace_processor/importers/proto/chrome_string_lookup.h
@@ -17,18 +17,26 @@
 #ifndef SRC_TRACE_PROCESSOR_IMPORTERS_PROTO_CHROME_STRING_LOOKUP_H_
 #define SRC_TRACE_PROCESSOR_IMPORTERS_PROTO_CHROME_STRING_LOOKUP_H_
 
-#include <map>
+#include <array>
 
-#include <optional>
+#include "protos/third_party/chromium/chrome_enums.pbzero.h"
 #include "src/trace_processor/storage/trace_storage.h"
 
-#include "perfetto/ext/base/string_view.h"
-
 namespace perfetto {
 namespace trace_processor {
 
 class ChromeStringLookup {
  public:
+  // Min and max known values for process and thread types.
+  constexpr static int32_t kProcessTypeMin =
+      ::perfetto::protos::chrome_enums::pbzero::ProcessType_MIN;
+  constexpr static int32_t kProcessTypeMax =
+      ::perfetto::protos::chrome_enums::pbzero::ProcessType_MAX;
+  constexpr static int32_t kThreadTypeMin =
+      ::perfetto::protos::chrome_enums::pbzero::ThreadType_MIN;
+  constexpr static int32_t kThreadTypeMax =
+      ::perfetto::protos::chrome_enums::pbzero::ThreadType_MAX;
+
   explicit ChromeStringLookup(TraceStorage* storage,
                               bool ignore_predefined_names_for_testing = false);
 
@@ -36,9 +44,9 @@
   StringId GetThreadName(int32_t thread_type) const;
 
  private:
-  std::map<int32_t /* ChromeProcessDescriptor::ProcessType */, StringId>
+  std::array<StringId, kProcessTypeMax - kProcessTypeMin + 1>
       chrome_process_name_ids_;
-  std::map<int32_t /* ChromeThreadDescriptor::ThreadType */, StringId>
+  std::array<StringId, kThreadTypeMax - kThreadTypeMin + 1>
       chrome_thread_name_ids_;
 };