[tracing] Turn StackFrame into struct.

base/trace_event/heap_profiler_allocation_context_tracker_unittest.cc

Index: base/trace_event/heap_profiler_allocation_context_tracker_unittest.cc
diff --git a/base/trace_event/heap_profiler_allocation_context_tracker_unittest.cc b/base/trace_event/heap_profiler_allocation_context_tracker_unittest.cc
index 05c60c722c317cca7bf6e52453a5faba1d7b1903..a39700e4fff4171d6701883d83d6a8ef98a85cdd 100644
--- a/base/trace_event/heap_profiler_allocation_context_tracker_unittest.cc
+++ b/base/trace_event/heap_profiler_allocation_context_tracker_unittest.cc
@@ -33,7 +33,7 @@ void AssertBacktraceEquals(const StackFrame(&expected_backtrace)[N]) {
           ->GetContextSnapshot();
 
   auto actual = std::begin(ctx.backtrace.frames);
-  auto actual_bottom = std::end(ctx.backtrace.frames);
+  auto actual_bottom = actual + ctx.backtrace.frame_count;

[Primiano Tucci (use gerrit), 2016/04/14 10:15:33]

why do we need this change? 

[Dmitry Skiba, 2016/04/15 07:01:40]

Because we want to check only valid frames, within frame_count.

   auto expected = std::begin(expected_backtrace);
   auto expected_bottom = std::end(expected_backtrace);
 
@@ -53,8 +53,7 @@ void AssertBacktraceEmpty() {
       AllocationContextTracker::GetInstanceForCurrentThread()
           ->GetContextSnapshot();
 
-  for (StackFrame frame : ctx.backtrace.frames)
-    ASSERT_EQ(nullptr, frame);
+  ASSERT_EQ(0u, ctx.backtrace.frame_count);
 }
 
 class AllocationContextTrackerTest : public testing::Test {
@@ -72,24 +71,22 @@ class AllocationContextTrackerTest : public testing::Test {
 };
 
 // Check that |TRACE_EVENT| macros push and pop to the pseudo stack correctly.
-// Also check that |GetContextSnapshot| fills the backtrace with null pointers
-// when the pseudo stack height is less than the capacity.
 TEST_F(AllocationContextTrackerTest, PseudoStackScopedTrace) {
-  StackFrame c = kCupcake;
-  StackFrame d = kDonut;
-  StackFrame e = kEclair;
-  StackFrame f = kFroyo;
+  StackFrame c = StackFrame::FromTraceEventName(kCupcake);
+  StackFrame d = StackFrame::FromTraceEventName(kDonut);
+  StackFrame e = StackFrame::FromTraceEventName(kEclair);
+  StackFrame f = StackFrame::FromTraceEventName(kFroyo);
 
   AssertBacktraceEmpty();
 
   {
     TRACE_EVENT0("Testing", kCupcake);
-    StackFrame frame_c[] = {c, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
+    StackFrame frame_c[] = {c};
     AssertBacktraceEquals(frame_c);
 
     {
       TRACE_EVENT0("Testing", kDonut);
-      StackFrame frame_cd[] = {c, d, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
+      StackFrame frame_cd[] = {c, d};
       AssertBacktraceEquals(frame_cd);
     }
 
@@ -97,7 +94,7 @@ TEST_F(AllocationContextTrackerTest, PseudoStackScopedTrace) {
 
     {
       TRACE_EVENT0("Testing", kEclair);
-      StackFrame frame_ce[] = {c, e, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
+      StackFrame frame_ce[] = {c, e};
       AssertBacktraceEquals(frame_ce);
     }
 
@@ -108,7 +105,7 @@ TEST_F(AllocationContextTrackerTest, PseudoStackScopedTrace) {
 
   {
     TRACE_EVENT0("Testing", kFroyo);
-    StackFrame frame_f[] = {f, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
+    StackFrame frame_f[] = {f};
     AssertBacktraceEquals(frame_f);
   }
 
@@ -118,15 +115,15 @@ TEST_F(AllocationContextTrackerTest, PseudoStackScopedTrace) {
 // Same as |PseudoStackScopedTrace|, but now test the |TRACE_EVENT_BEGIN| and
 // |TRACE_EVENT_END| macros.
 TEST_F(AllocationContextTrackerTest, PseudoStackBeginEndTrace) {
-  StackFrame c = kCupcake;
-  StackFrame d = kDonut;
-  StackFrame e = kEclair;
-  StackFrame f = kFroyo;
+  StackFrame c = StackFrame::FromTraceEventName(kCupcake);
+  StackFrame d = StackFrame::FromTraceEventName(kDonut);
+  StackFrame e = StackFrame::FromTraceEventName(kEclair);
+  StackFrame f = StackFrame::FromTraceEventName(kFroyo);
 
-  StackFrame frame_c[] = {c, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
-  StackFrame frame_cd[] = {c, d, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
-  StackFrame frame_ce[] = {c, e, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
-  StackFrame frame_f[] = {f, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
+  StackFrame frame_c[] = {c};
+  StackFrame frame_cd[] = {c, d};
+  StackFrame frame_ce[] = {c, e};
+  StackFrame frame_f[] = {f};
 
   AssertBacktraceEmpty();
 
@@ -156,15 +153,15 @@ TEST_F(AllocationContextTrackerTest, PseudoStackBeginEndTrace) {
 }
 
 TEST_F(AllocationContextTrackerTest, PseudoStackMixedTrace) {
-  StackFrame c = kCupcake;
-  StackFrame d = kDonut;
-  StackFrame e = kEclair;
-  StackFrame f = kFroyo;
+  StackFrame c = StackFrame::FromTraceEventName(kCupcake);
+  StackFrame d = StackFrame::FromTraceEventName(kDonut);
+  StackFrame e = StackFrame::FromTraceEventName(kEclair);
+  StackFrame f = StackFrame::FromTraceEventName(kFroyo);
 
-  StackFrame frame_c[] = {c, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
-  StackFrame frame_cd[] = {c, d, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
-  StackFrame frame_e[] = {e, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
-  StackFrame frame_ef[] = {e, f, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
+  StackFrame frame_c[] = {c};
+  StackFrame frame_cd[] = {c, d};
+  StackFrame frame_e[] = {e};
+  StackFrame frame_ef[] = {e, f};
 
   AssertBacktraceEmpty();
 
@@ -194,6 +191,9 @@ TEST_F(AllocationContextTrackerTest, PseudoStackMixedTrace) {
 }
 
 TEST_F(AllocationContextTrackerTest, BacktraceTakesTop) {
+  StackFrame c = StackFrame::FromTraceEventName(kCupcake);
+  StackFrame f = StackFrame::FromTraceEventName(kFroyo);
+
   // Push 12 events onto the pseudo stack.
   TRACE_EVENT0("Testing", kCupcake);
   TRACE_EVENT0("Testing", kCupcake);
@@ -217,16 +217,16 @@ TEST_F(AllocationContextTrackerTest, BacktraceTakesTop) {
             ->GetContextSnapshot();
 
     // The pseudo stack relies on pointer equality, not deep string comparisons.
-    ASSERT_EQ(kCupcake, ctx.backtrace.frames[0]);
-    ASSERT_EQ(kFroyo, ctx.backtrace.frames[11]);
+    ASSERT_EQ(c, ctx.backtrace.frames[0]);
+    ASSERT_EQ(f, ctx.backtrace.frames[11]);
   }
 
   {
     AllocationContext ctx =
         AllocationContextTracker::GetInstanceForCurrentThread()
             ->GetContextSnapshot();
-    ASSERT_EQ(kCupcake, ctx.backtrace.frames[0]);
-    ASSERT_EQ(kFroyo, ctx.backtrace.frames[11]);
+    ASSERT_EQ(c, ctx.backtrace.frames[0]);
+    ASSERT_EQ(f, ctx.backtrace.frames[11]);
   }
 }
 
@@ -239,8 +239,8 @@ TEST_F(AllocationContextTrackerTest, SetCurrentThreadName) {
   AllocationContext ctx1 =
       AllocationContextTracker::GetInstanceForCurrentThread()
           ->GetContextSnapshot();
-  ASSERT_EQ(kThread1, ctx1.backtrace.frames[0]);
-  ASSERT_EQ(kCupcake, ctx1.backtrace.frames[1]);
+  ASSERT_EQ(StackFrame::FromThreadName(kThread1), ctx1.backtrace.frames[0]);
+  ASSERT_EQ(StackFrame::FromTraceEventName(kCupcake), ctx1.backtrace.frames[1]);
 
   // Test if the thread name is reset.
   const char kThread2[] = "thread2";
@@ -248,8 +248,8 @@ TEST_F(AllocationContextTrackerTest, SetCurrentThreadName) {
   AllocationContext ctx2 =
       AllocationContextTracker::GetInstanceForCurrentThread()
           ->GetContextSnapshot();
-  ASSERT_EQ(kThread2, ctx2.backtrace.frames[0]);
-  ASSERT_EQ(kCupcake, ctx2.backtrace.frames[1]);
+  ASSERT_EQ(StackFrame::FromThreadName(kThread2), ctx2.backtrace.frames[0]);
+  ASSERT_EQ(StackFrame::FromTraceEventName(kCupcake), ctx2.backtrace.frames[1]);
 }
 
 TEST_F(AllocationContextTrackerTest, TrackTaskContext) {