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

base/profiler/stack_sampling_profiler_unittest.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 <cstdlib>
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_vector.h"
 #include "base/message_loop/message_loop.h"
@@ skipping 497 matching lines @@
       sample,
       &TargetThread::SignalAndWaitUntilSignaled);
   ASSERT_TRUE(end_frame != sample.end())
       << "Function at "
       << MaybeFixupFunctionAddressForILT(reinterpret_cast<const void*>(
           &TargetThread::SignalAndWaitUntilSignaled))
       << " was not found in stack:\n"
       << FormatSampleForDiagnosticOutput(sample, profile.modules);
 
   if (wait_until_unloaded) {
-    // The stack should look like this, resulting in two frames between
-    // SignalAndWaitUntilSignaled and the last frame, which should be the one in
-    // the now-unloaded library:
+    // The stack should look like this, resulting one frame after
+    // SignalAndWaitUntilSignaled. The frame in the now-unloaded library is not
+    // recorded since we can't get module information.
     //
     // ... WaitableEvent and system frames ...
     // TargetThread::SignalAndWaitUntilSignaled
     // TargetThread::OtherLibraryCallback
-    // InvokeCallbackFunction (in other library, now unloaded)
-    EXPECT_EQ(2, (sample.end() - 1) - end_frame)
+    EXPECT_EQ(2, sample.end() - end_frame)
         << "Stack:\n"
         << FormatSampleForDiagnosticOutput(sample, profile.modules);
   } else {
     // We didn't wait for the asynchonous unloading to complete, so the results
     // are non-deterministic: if the library finished unloading we should have
     // the same stack as |wait_until_unloaded|, if not we should have the full
     // stack. The important thing is that we should not crash.
 
     if ((sample.end() - 1) - end_frame == 2) {
       // This is the same case as |wait_until_unloaded|.
@@ skipping 417 matching lines @@
 #if defined(STACK_SAMPLING_PROFILER_SUPPORTED)
 #define MAYBE_UnloadedLibrary UnloadedLibrary
 #else
 #define MAYBE_UnloadedLibrary DISABLED_UnloadedLibrary
 #endif
 TEST(StackSamplingProfilerTest, MAYBE_UnloadedLibrary) {
   TestLibraryUnload(true);
 }
 
 }  // namespace base