Add heap allocator usage to task profiler.

base/debug/scoped_thread_heap_usage.h

Index: base/debug/scoped_thread_heap_usage.h
diff --git a/base/debug/scoped_thread_heap_usage.h b/base/debug/scoped_thread_heap_usage.h
index a843fc93d0c41398e8e25d68acc9480a78d9d3d3..d5fd805171ae33e6d26791a64cdd165a8e97110c 100644
--- a/base/debug/scoped_thread_heap_usage.h
+++ b/base/debug/scoped_thread_heap_usage.h
@@ -18,6 +18,33 @@ struct AllocatorDispatch;
 
 namespace debug {
 
+// Used to store the heap allocator usage in a scope.
+struct ThreadAllocatorUsage {
+  // The cumulative number of allocation operations.
+  uint64_t alloc_ops;
+
+  // The cumulative number of allocated bytes. Where available, this is
+  // inclusive heap padding and estimated or actual heap overhead.
+  uint64_t alloc_bytes;
+
+  // Where available, cumulative number of heap padding heap
+  // and overhead bytes.
+  uint64_t alloc_overhead_bytes;
+
+  // The cumulative number of free operations.
+  uint64_t free_ops;
+
+  // The cumulative number of bytes freed.
+  // Only recorded if the underlying heap shim can return the size of an
+  // allocation.
+  uint64_t free_bytes;
+
+  // The maximal value of alloc_bytes - free_bytes seen for this thread.
+  // Only recorded if the underlying heap shim supports returning the size of
+  // an allocation.
+  uint64_t max_allocated_bytes;
+};
+
 // By keeping a tally on heap operations, it's possible to track:
 // - the number of alloc/free operations, where a realloc is zero or one
 //   of each, depending on the input parameters (see man realloc).
@@ -31,60 +58,37 @@ namespace debug {
 // Note that this depends on the capabilities of the underlying heap shim. If
 // that shim can not yield a size estimate for an allocation, it's not possible
 // to keep track of overhead, freed bytes and the allocation high water mark.
-class BASE_EXPORT ScopedThreadHeapUsage {
+class BASE_EXPORT HeapUsageTracker {
  public:
-  struct ThreadAllocatorUsage {
-    // The cumulative number of allocation operations.
-    uint64_t alloc_ops;
-
-    // The cumulative number of allocated bytes. Where available, this is
-    // inclusive heap padding and estimated or actual heap overhead.
-    uint64_t alloc_bytes;
-
-    // Where available, cumulative number of heap padding heap
-    // and overhead bytes.
-    uint64_t alloc_overhead_bytes;
-
-    // The cumulative number of free operations.
-    uint64_t free_ops;
-
-    // The cumulative number of bytes freed.
-    // Only recorded if the underlying heap shim can return the size of an
-    // allocation.
-    uint64_t free_bytes;
+  HeapUsageTracker();
+  ~HeapUsageTracker();
 
-    // The maximal value of alloc_bytes - free_bytes seen for this thread.
-    // Only recorded if the underlying heap shim supports returning the size of
-    // an allocation.
-    uint64_t max_allocated_bytes;
-  };
+  void Start();
+  void Stop(bool usage_is_exclusive);
 
-  ScopedThreadHeapUsage();
-  ~ScopedThreadHeapUsage();
-
-  const ThreadAllocatorUsage& usage_at_creation() const {
-    return usage_at_creation_;
-  }
+  const ThreadAllocatorUsage& usage() const { return usage_; }
 
   // Returns this thread's allocator usage from the creation of the innermost
   // enclosing ScopedThreadHeapUsage instance, if any. Note that this is
   // inclusive allocator usage in all inner scopes.
   static ThreadAllocatorUsage CurrentUsage();
 
-  // Initializes the TLS machinery this class uses. Must be called before
-  // creating instances of this class.
-  static void Initialize();
-
   // Enables the heap intercept. May only be called once, and only if the heap
   // shim is available, e.g. if BUILDFLAG(USE_EXPERIMENTAL_ALLOCATOR_SHIM) is
   // true.
   static void EnableHeapTracking();
 
+  // Returns true iff heap tracking is enabled.
+  static bool IsHeapTrackingEnabled();
+
  protected:
   // Exposed for testing only - note that it's safe to re-EnableHeapTracking()
   // after calling this function in tests.
   static void DisableHeapTrackingForTesting();
 
+  // Exposed for testing only.
+  static void EnsureTLSInitializedForTesting();
+
   // Exposed to allow testing the shim without inserting it in the allocator
   // shim chain.
   static base::allocator::AllocatorDispatch* GetDispatchForTesting();
@@ -93,8 +97,12 @@ class BASE_EXPORT ScopedThreadHeapUsage {
   static void EnsureTLSInitialized();
 
   ThreadChecker thread_checker_;
-  // The allocator usage captured at creation of this instance.
-  ThreadAllocatorUsage usage_at_creation_;
+
+  // The allocator usage at Start(), or the difference from Start() to Stop().
+  ThreadAllocatorUsage usage_;
+
+  // This thread's allocator usage, non-null from Start() to Stop().
+  ThreadAllocatorUsage* thread_usage_;
 };
 
 }  // namespace debug