Add function to trace stack using frame pointers.

base/debug/stack_trace_unittest.cc

Index: base/debug/stack_trace_unittest.cc
diff --git a/base/debug/stack_trace_unittest.cc b/base/debug/stack_trace_unittest.cc
index 9abedba6bafd91160989fb718cebc78b4fafbdf6..af53a147766cad1969b0ac8cf52b8ec3dc621e17 100644
--- a/base/debug/stack_trace_unittest.cc
+++ b/base/debug/stack_trace_unittest.cc
@@ -238,5 +238,61 @@ TEST_F(StackTraceTest, itoa_r) {
 }
 #endif  // defined(OS_POSIX) && !defined(OS_ANDROID)
 
+#if HAVE_TRACE_STACK_FRAME_POINTERS
+
+TEST_F(StackTraceTest, TraceStackFramePointers) {
+  const void* fp_frames[10];
+  size_t fp_frame_count =
+      TraceStackFramePointers(fp_frames, arraysize(fp_frames), 0);
+
+  // We expect to fill the whole frame array
+  ASSERT_EQ(arraysize(fp_frames), fp_frame_count);
+
+  // Compare against StackTrace
+
+  StackTrace stack_trace;
+  size_t frame_count = 0;
+  const void* const* frames = stack_trace.Addresses(&frame_count);
+
+  // Find offsets into both frame arrays that have matching frames
+  size_t fp_frames_offset = 0;
+  size_t frames_offset = 0;
+  bool found_matching_frame = false;
+  for (;fp_frames_offset != fp_frame_count; ++fp_frames_offset) {
+    const void* frame = fp_frames[fp_frames_offset];
+    for (frames_offset = 0; frames_offset != frame_count; ++frames_offset) {
+      if (frames[frames_offset] == frame) {
+        found_matching_frame = true;
+        break;
+      }
+    }
+    if (found_matching_frame) {
+      break;
+    }
+  }
+
+  ASSERT_TRUE(found_matching_frame) <<
+      "StackTrace class and TraceStackFramePointers function produced " <<
+      "completely different traces.";
+
+  // fp_frames[0] points somewhere inside this function and differs from
+  // location reported by StackFrame (since invocations are on different
+  // lines). However fp_frames[1] points to the caller function, and should
+  // be in both frame arrays.
+  ASSERT_EQ(fp_frames_offset, 1u);
+
+  size_t check_depth = std::min(fp_frame_count - fp_frames_offset,
+                                frame_count - frames_offset);
+  for (size_t i = 0; i != check_depth; ++i) {
+    size_t fp_frame_index = i + fp_frames_offset;
+    size_t frame_index = i + frames_offset;
+    EXPECT_EQ(frames[frame_index], fp_frames[fp_frame_index]) <<
+        "Where frame_index = " << frame_index << ", " <<
+        "fp_frame_index = " << fp_frame_index;
+  }
+}
+
+#endif  // HAVE_TRACE_STACK_FRAME_POINTERS
+
 }  // namespace debug
 }  // namespace base