Add a histogram for total private memory footprint.

chrome/browser/metrics/process_memory_metrics_emitter_browsertest.cc

 // Copyright 2017 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 "chrome/browser/metrics/process_memory_metrics_emitter.h"
 
 #include "base/memory/ref_counted.h"
 #include "base/message_loop/message_loop.h"
 #include "base/test/histogram_tester.h"
 #include "base/test/trace_event_analyzer.h"
@@ skipping 68 matching lines @@
   if (check_minimum)
     EXPECT_GT(samples->sum(), 0u) << name;
 
   // As a sanity check, no memory stat should exceed 1 GB.
   int64_t maximum_expected_size = 1ll << 30;
   EXPECT_LT(samples->sum(), maximum_expected_size) << name;
 }
 
 void CheckAllMemoryMetrics(const base::HistogramTester& histogram_tester,
                            int count) {
-#if (defined(OS_MACOSX) && !defined(OS_IOS)) || defined(OS_LINUX) || \
-    defined(OS_ANDROID)
-  bool private_footprint_implemented = true;
-#else
-  bool private_footprint_implemented = false;
-#endif
-
   CheckMemoryMetric("Memory.Experimental.Browser2.Malloc", histogram_tester,
                     count, true);
   CheckMemoryMetric("Memory.Experimental.Browser2.Resident", histogram_tester,
                     count, true);
   CheckMemoryMetric("Memory.Experimental.Browser2.PrivateMemoryFootprint",
-                    histogram_tester, count, private_footprint_implemented);
+                    histogram_tester, count, true);
   CheckMemoryMetric("Memory.Experimental.Renderer2.Malloc", histogram_tester,
                     count, true);
   CheckMemoryMetric("Memory.Experimental.Renderer2.Resident", histogram_tester,
                     count, true);
   CheckMemoryMetric("Memory.Experimental.Renderer2.BlinkGC", histogram_tester,
                     count, false);
   CheckMemoryMetric("Memory.Experimental.Renderer2.PartitionAlloc",
                     histogram_tester, count, false);
   CheckMemoryMetric("Memory.Experimental.Renderer2.V8", histogram_tester, count,
                     true);
   CheckMemoryMetric("Memory.Experimental.Renderer2.PrivateMemoryFootprint",
-                    histogram_tester, count, private_footprint_implemented);
+                    histogram_tester, count, true);
+  CheckMemoryMetric("Memory.Experimental.Total2.PrivateMemoryFootprint",
+                    histogram_tester, count, true);
 }
 
 }  // namespace
 
 class ProcessMemoryMetricsEmitterTest : public InProcessBrowserTest {
  public:
   ProcessMemoryMetricsEmitterTest() {}
   ~ProcessMemoryMetricsEmitterTest() override {}
 
  private:
@@ skipping 101 matching lines @@
     // Only the last emitter should stop the run loop.
     auto emitter = base::MakeRefCounted<ProcessMemoryMetricsEmitterFake>(
         (i == count - 1) ? &run_loop : nullptr);
     emitter->FetchAndEmitProcessMemoryMetrics();
   }
 
   run_loop.Run();
 
   CheckAllMemoryMetrics(histogram_tester, count);
 }