Add unit-test for SharedSampler handling of zero-thread processes.

chrome/browser/task_manager/sampling/shared_sampler_win_defines.h

Index: chrome/browser/task_manager/sampling/shared_sampler_win_defines.h
diff --git a/chrome/browser/task_manager/sampling/shared_sampler_win_defines.h b/chrome/browser/task_manager/sampling/shared_sampler_win_defines.h
new file mode 100644
index 0000000000000000000000000000000000000000..736f388edd5510bed2e437b011b6306e89096cdc
--- /dev/null
+++ b/chrome/browser/task_manager/sampling/shared_sampler_win_defines.h
@@ -0,0 +1,113 @@
+// Copyright 2016 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.
+
+#ifndef CHROME_BROWSER_TASK_MANAGER_SAMPLING_SHARED_SAMPLER_WIN_DEFINES_H_
+#define CHROME_BROWSER_TASK_MANAGER_SAMPLING_SHARED_SAMPLER_WIN_DEFINES_H_
+
+#include <windows.h>
+#include <winternl.h>
+
+namespace task_manager {
+
+// From <wdm.h>
+typedef LONG KPRIORITY;
+typedef LONG KWAIT_REASON;  // Full definition is in wdm.h
+
+// From ntddk.h
+typedef struct _VM_COUNTERS {
+  SIZE_T PeakVirtualSize;
+  SIZE_T VirtualSize;
+  ULONG PageFaultCount;
+  // Padding here in 64-bit
+  SIZE_T PeakWorkingSetSize;
+  SIZE_T WorkingSetSize;
+  SIZE_T QuotaPeakPagedPoolUsage;
+  SIZE_T QuotaPagedPoolUsage;
+  SIZE_T QuotaPeakNonPagedPoolUsage;
+  SIZE_T QuotaNonPagedPoolUsage;
+  SIZE_T PagefileUsage;
+  SIZE_T PeakPagefileUsage;
+} VM_COUNTERS;
+
+// Two possibilities available from here:
+// http://stackoverflow.com/questions/28858849/where-is-system-information-class-defined
+
+typedef enum _SYSTEM_INFORMATION_CLASS {
+  SystemProcessInformation = 5,  // This is the number that we need.
+} SYSTEM_INFORMATION_CLASS;
+
+// https://msdn.microsoft.com/en-us/library/gg750647.aspx?f=255&MSPPError=-2147217396
+typedef struct {
+  HANDLE UniqueProcess;  // Actually process ID
+  HANDLE UniqueThread;   // Actually thread ID
+} CLIENT_ID;
+
+// From http://alax.info/blog/1182, with corrections and modifications
+// Originally from
+// http://undocumented.ntinternals.net/index.html?page=UserMode%2FUndocumented%20Functions%2FSystem%20Information%2FStructures%2FSYSTEM_THREAD.html
+struct SYSTEM_THREAD_INFORMATION {
+  ULONGLONG KernelTime;
+  ULONGLONG UserTime;
+  ULONGLONG CreateTime;
+  ULONG WaitTime;
+  // Padding here in 64-bit
+  PVOID StartAddress;
+  CLIENT_ID ClientId;
+  KPRIORITY Priority;
+  LONG BasePriority;
+  ULONG ContextSwitchCount;
+  ULONG State;
+  KWAIT_REASON WaitReason;
+};
+#if _M_X64
+static_assert(sizeof(SYSTEM_THREAD_INFORMATION) == 80,
+              "Structure size mismatch");
+#else
+static_assert(sizeof(SYSTEM_THREAD_INFORMATION) == 64,
+              "Structure size mismatch");
+#endif
+
+// From http://alax.info/blog/1182, with corrections and modifications
+// Originally from
+// http://undocumented.ntinternals.net/index.html?page=UserMode%2FUndocumented%20Functions%2FSystem%20Information%2FStructures%2FSYSTEM_THREAD.html
+struct SYSTEM_PROCESS_INFORMATION {
+  ULONG NextEntryOffset;
+  ULONG NumberOfThreads;
+  // http://processhacker.sourceforge.net/doc/struct___s_y_s_t_e_m___p_r_o_c_e_s_s___i_n_f_o_r_m_a_t_i_o_n.html
+  ULONGLONG WorkingSetPrivateSize;
+  ULONG HardFaultCount;
+  ULONG Reserved1;
+  ULONGLONG CycleTime;
+  ULONGLONG CreateTime;
+  ULONGLONG UserTime;
+  ULONGLONG KernelTime;
+  UNICODE_STRING ImageName;
+  KPRIORITY BasePriority;
+  HANDLE ProcessId;
+  HANDLE ParentProcessId;
+  ULONG HandleCount;
+  ULONG Reserved2[2];
+  // Padding here in 64-bit
+  VM_COUNTERS VirtualMemoryCounters;
+  size_t Reserved3;
+  IO_COUNTERS IoCounters;
+  SYSTEM_THREAD_INFORMATION Threads[1];
+};
+#if _M_X64
+static_assert(sizeof(SYSTEM_PROCESS_INFORMATION) == 336,
+              "Structure size mismatch");
+#else
+static_assert(sizeof(SYSTEM_PROCESS_INFORMATION) == 248,
+              "Structure size mismatch");
+#endif
+
+typedef NTSTATUS(WINAPI* NTQUERYSYSTEMINFORMATION)(
+    SYSTEM_INFORMATION_CLASS SystemInformationClass,
+    PVOID SystemInformation,
+    ULONG SystemInformationLength,
+    PULONG ReturnLength);
+
+}  // namespace task_manager
+
+#endif  //  CHROME_BROWSER_TASK_MANAGER_SAMPLING_SHARED_SAMPLER_WIN_DEFINES_H_