trace_processor: rename Table::size() -> Table::row_count()

Future tables use size as a column inside the table and we get bad name
clashes if we don't rename this method.

Change-Id: I73db86f24901e2fdce2a6b9b063efec702fbbf8b
diff --git a/src/trace_processor/export_json_unittest.cc b/src/trace_processor/export_json_unittest.cc
index 02fe44d..4d72fcc 100644
--- a/src/trace_processor/export_json_unittest.cc
+++ b/src/trace_processor/export_json_unittest.cc
@@ -1150,7 +1150,7 @@
 
   uint32_t frame_row_id_1 = storage->mutable_stack_profile_frames()->Insert(
       {/*name_id=*/0, module_row_id_1, 0x42});
-  uint32_t symbol_set_id = storage->symbol_table().size();
+  uint32_t symbol_set_id = storage->symbol_table().row_count();
   storage->mutable_symbol_table()->Insert(
       {symbol_set_id, storage->InternString("foo_func"),
        storage->InternString("foo_file"), 66});
@@ -1159,7 +1159,7 @@
 
   uint32_t frame_row_id_2 = storage->mutable_stack_profile_frames()->Insert(
       {/*name_id=*/0, module_row_id_2, 0x4242});
-  symbol_set_id = storage->symbol_table().size();
+  symbol_set_id = storage->symbol_table().row_count();
   storage->mutable_symbol_table()->Insert(
       {symbol_set_id, storage->InternString("bar_func"),
        storage->InternString("bar_file"), 77});