Revert of [tracing] Turn StackFrame into struct.

base/trace_event/heap_profiler_heap_dump_writer_unittest.cc

Index: base/trace_event/heap_profiler_heap_dump_writer_unittest.cc
diff --git a/base/trace_event/heap_profiler_heap_dump_writer_unittest.cc b/base/trace_event/heap_profiler_heap_dump_writer_unittest.cc
index e7850a142cb735fe6700a1b54db94449185ddb41..8faa5cf2f91a1be164bf5973f6b17c0466766f80 100644
--- a/base/trace_event/heap_profiler_heap_dump_writer_unittest.cc
+++ b/base/trace_event/heap_profiler_heap_dump_writer_unittest.cc
@@ -22,15 +22,13 @@
 
 namespace {
 
-using base::trace_event::StackFrame;
-
 // Define all strings once, because the deduplicator requires pointer equality,
 // and string interning is unreliable.
-StackFrame kBrowserMain = StackFrame::FromTraceEventName("BrowserMain");
-StackFrame kRendererMain = StackFrame::FromTraceEventName("RendererMain");
-StackFrame kCreateWidget = StackFrame::FromTraceEventName("CreateWidget");
-StackFrame kInitialize = StackFrame::FromTraceEventName("Initialize");
-StackFrame kGetBitmap = StackFrame::FromTraceEventName("GetBitmap");
+const char kBrowserMain[] = "BrowserMain";
+const char kRendererMain[] = "RendererMain";
+const char kCreateWidget[] = "CreateWidget";
+const char kInitialize[] = "Initialize";
+const char kGetBitmap[] = "GetBitmap";
 
 const char kInt[] = "int";
 const char kBool[] = "bool";
@@ -180,10 +178,9 @@
 TEST(HeapDumpWriterTest, BacktraceTypeNameTable) {
   hash_map<AllocationContext, AllocationMetrics> metrics_by_context;
 
-  AllocationContext ctx;
+  AllocationContext ctx = AllocationContext::Empty();
   ctx.backtrace.frames[0] = kBrowserMain;
   ctx.backtrace.frames[1] = kCreateWidget;
-  ctx.backtrace.frame_count = 2;
   ctx.type_name = kInt;
 
   // 10 bytes with context { type: int, bt: [BrowserMain, CreateWidget] }.
@@ -196,7 +193,6 @@
 
   ctx.backtrace.frames[0] = kRendererMain;
   ctx.backtrace.frames[1] = kInitialize;
-  ctx.backtrace.frame_count = 2;
 
   // 30 bytes with context { type: bool, bt: [RendererMain, Initialize] }.
   metrics_by_context[ctx] = {30, 30};
@@ -271,22 +267,19 @@
 TEST(HeapDumpWriterTest, InsignificantValuesNotDumped) {
   hash_map<AllocationContext, AllocationMetrics> metrics_by_context;
 
-  AllocationContext ctx;
+  AllocationContext ctx = AllocationContext::Empty();
   ctx.backtrace.frames[0] = kBrowserMain;
   ctx.backtrace.frames[1] = kCreateWidget;
-  ctx.backtrace.frame_count = 2;
 
   // 0.5 KiB and 1 chunk in BrowserMain -> CreateWidget itself.
   metrics_by_context[ctx] = {512, 1};
 
   // 1 MiB and 1 chunk in BrowserMain -> CreateWidget -> GetBitmap.
   ctx.backtrace.frames[2] = kGetBitmap;
-  ctx.backtrace.frame_count = 3;
   metrics_by_context[ctx] = {1024 * 1024, 1};
 
   // 0.5 KiB and 1 chunk in BrowserMain -> CreateWidget -> Initialize.
   ctx.backtrace.frames[2] = kInitialize;
-  ctx.backtrace.frame_count = 3;
   metrics_by_context[ctx] = {512, 1};
 
   auto sf_deduplicator = WrapUnique(new StackFrameDeduplicator);