Record Chrome trace events in tcmalloc heap profiles

third_party/tcmalloc/chromium/src/heap-profiler.cc

Index: third_party/tcmalloc/chromium/src/heap-profiler.cc
diff --git a/third_party/tcmalloc/chromium/src/heap-profiler.cc b/third_party/tcmalloc/chromium/src/heap-profiler.cc
index 0b07a5e8662da230e481839dcb5f62b521f9359d..1085303789d7f7e2bea424558aabd24d1d6659e0 100644
--- a/third_party/tcmalloc/chromium/src/heap-profiler.cc
+++ b/third_party/tcmalloc/chromium/src/heap-profiler.cc
@@ -222,6 +222,9 @@ static int64 last_dump_time = 0;      // The time of the last dump
 static HeapProfileTable* heap_profile = NULL;  // the heap profile table
 static DeepHeapProfile* deep_profile = NULL;  // deep memory profiler
 
+// Callback an appplication can use to generate its own "stacks".
+static PseudoStackGenerator pseudo_stack_generator = NULL;
+
 //----------------------------------------------------------------------
 // Profile generation
 //----------------------------------------------------------------------
@@ -374,7 +377,11 @@ static void MaybeDumpProfileLocked() {
 static void RecordAlloc(const void* ptr, size_t bytes, int skip_count) {
   // Take the stack trace outside the critical section.
   void* stack[HeapProfileTable::kMaxStackDepth];
-  int depth = HeapProfileTable::GetCallerStackTrace(skip_count + 1, stack);
+  // If using pseudo-stacks then use a callback to get the stack, otherwise
+  // use normal stack unwinding.
+  int depth = pseudo_stack_generator ?
+      (*pseudo_stack_generator)(stack) :
+      HeapProfileTable::GetCallerStackTrace(skip_count + 1, stack);
   SpinLockHolder l(&heap_lock);
   if (is_on) {
     heap_profile->RecordAlloc(ptr, bytes, depth, stack);
@@ -542,12 +549,25 @@ extern "C" void HeapProfilerStart(const char* prefix) {
     RAW_CHECK(MallocHook::AddDeleteHook(&DeleteHook), "");
   }
 
-  // Copy filename prefix
-  RAW_DCHECK(filename_prefix == NULL, "");
-  const int prefix_length = strlen(prefix);
-  filename_prefix = reinterpret_cast<char*>(ProfilerMalloc(prefix_length + 1));
-  memcpy(filename_prefix, prefix, prefix_length);
-  filename_prefix[prefix_length] = '\0';
+  // Copy filename prefix if provided.
+  if (prefix) {
+    RAW_DCHECK(filename_prefix == NULL, "");
+    const int prefix_length = strlen(prefix);
+    filename_prefix =
+        reinterpret_cast<char*>(ProfilerMalloc(prefix_length + 1));
+    memcpy(filename_prefix, prefix, prefix_length);
+    filename_prefix[prefix_length] = '\0';
+  }
+}
+
+extern "C" void HeapProfilerWithPseudoStackStart(
+    PseudoStackGenerator callback) {
+  {
+    // Ensure the callback is set before allocations can be recorded.
+    SpinLockHolder l(&heap_lock);
+    pseudo_stack_generator = callback;
+  }
+  HeapProfilerStart(NULL);
 }
 
 extern "C" void IterateAllocatedObjects(AddressVisitor visitor, void* data) {