Stack sampling profiler: fix off-by-one error on truncated stacks

base/profiler/native_stack_sampler_win.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <objbase.h>
 #include <windows.h>
 #include <winternl.h>
 
 #include <cstdlib>
 #include <map>
@@ skipping 130 matching lines @@
 // recording the instruction pointers for each frame in |instruction_pointers|.
 int RecordStack(CONTEXT* context, int max_stack_size,
                 const void* instruction_pointers[],
                 ScopedModuleHandle modules[]) {
 #ifdef _WIN64
   Win32StackFrameUnwinder frame_unwinder;
   int i = 0;
   for (; (i < max_stack_size) && context->Rip; ++i) {
     instruction_pointers[i] = reinterpret_cast<const void*>(context->Rip);
     if (!frame_unwinder.TryUnwind(context, &modules[i]))
-      return i + 1;
+      return i;
   }
   return i;
 #else
   return 0;
 #endif
 }
 
 // Gets the unique build ID for a module. Windows build IDs are created by a
 // concatenation of a GUID and AGE fields found in the headers of a module. The
 // GUID is stored in the first 16 bytes and the AGE is stored in the last 4
@@ skipping 333 matching lines @@
   if (thread_handle) {
     return scoped_ptr<NativeStackSampler>(new NativeStackSamplerWin(
         win::ScopedHandle(thread_handle),
         test_delegate));
   }
 #endif
   return scoped_ptr<NativeStackSampler>();
 }
 
 }  // namespace base