Add TRACE_COUNTER_WITH_TIMESTAMPx macros.

base::ProcessMetrics::GetCPUUsage() gives access to the % of CPU usage
for the current process in the time interval [a, b], where a is the
timestamp of the previous call to the method and b is the current
timestamp.

In order to display a correct CPU usage graph in about:tracing from the
values returned by base::ProcessMetrics::GetCPUUsage(), we need a way
to emit a counter event with timestamp |b| when we read the CPU usage at
timestamp |a|.

This CL introduces 2 TRACE_COUNTER_WITH_TIMESTAMPx macros that can emit
a counter event with a custom timestamp.

BUG=553266

Review URL: https://codereview.chromium.org/1432873002

Cr-Commit-Position: refs/heads/master@{#361807}

3 files changed, 69 insertions, 0 deletions

diff --git a/base/trace_event/common/trace_event_common.h b/base/trace_event/common/trace_event_common.h
index 16a9a37..cae3670 100644
--- a/base/trace_event/common/trace_event_common.h
+++ b/base/trace_event/common/trace_event_common.h
@@ -484,6 +484,20 @@
                            static_cast<int>(value1_val), value2_name,       \
                            static_cast<int>(value2_val))
 
+// Similar to TRACE_COUNTERx, but with a custom |timestamp| provided.
+#define TRACE_COUNTER_WITH_TIMESTAMP1(category_group, name, timestamp, value) \
+  INTERNAL_TRACE_EVENT_ADD_WITH_TIMESTAMP(                                    \
+      TRACE_EVENT_PHASE_COUNTER, category_group, name, timestamp,             \
+      TRACE_EVENT_FLAG_NONE, "value", static_cast<int>(value))
+
+#define TRACE_COUNTER_WITH_TIMESTAMP2(category_group, name, timestamp,      \
+                                      value1_name, value1_val, value2_name, \
+                                      value2_val)                           \
+  INTERNAL_TRACE_EVENT_ADD_WITH_TIMESTAMP(                                  \
+      TRACE_EVENT_PHASE_COUNTER, category_group, name, timestamp,           \
+      TRACE_EVENT_FLAG_NONE, value1_name, static_cast<int>(value1_val),     \
+      value2_name, static_cast<int>(value2_val))
+
 // Records the value of a counter called "name" immediately. Value
 // must be representable as a 32 bit integer.
 // - category and name strings must have application lifetime (statics or
diff --git a/base/trace_event/trace_event.h b/base/trace_event/trace_event.h
index 95ea215..14448e2 100644
--- a/base/trace_event/trace_event.h
+++ b/base/trace_event/trace_event.h
@@ -302,6 +302,23 @@ TRACE_EVENT_API_CLASS_EXPORT extern \
 
 // Implementation detail: internal macro to create static category and add
 // event if the category is enabled.
+#define INTERNAL_TRACE_EVENT_ADD_WITH_TIMESTAMP(phase, category_group, name, \
+                                                timestamp, flags, ...)       \
+  do {                                                                       \
+    INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category_group);                  \
+    if (INTERNAL_TRACE_EVENT_CATEGORY_GROUP_ENABLED_FOR_RECORDING_MODE()) {  \
+      trace_event_internal::AddTraceEventWithThreadIdAndTimestamp(           \
+          phase, INTERNAL_TRACE_EVENT_UID(category_group_enabled), name,     \
+          trace_event_internal::kNoId, trace_event_internal::kNoId,          \
+          TRACE_EVENT_API_CURRENT_THREAD_ID,                                 \
+          base::TimeTicks::FromInternalValue(timestamp),                     \
+          flags | TRACE_EVENT_FLAG_EXPLICIT_TIMESTAMP,                       \
+          trace_event_internal::kNoId, ##__VA_ARGS__);                       \
+    }                                                                        \
+  } while (0)
+
+// Implementation detail: internal macro to create static category and add
+// event if the category is enabled.
 #define INTERNAL_TRACE_EVENT_ADD_WITH_ID_TID_AND_TIMESTAMP(phase, \
         category_group, name, id, thread_id, timestamp, flags, ...) \
     do { \
diff --git a/base/trace_event/trace_event_unittest.cc b/base/trace_event/trace_event_unittest.cc
index 084c250..533a298 100644
--- a/base/trace_event/trace_event_unittest.cc
+++ b/base/trace_event/trace_event_unittest.cc
@@ -459,6 +459,11 @@ void TraceWithAllMacroVariants(WaitableEvent* task_complete_event) {
                    "a", 30000,
                    "b", 1415);
 
+    TRACE_COUNTER_WITH_TIMESTAMP1("all", "TRACE_COUNTER_WITH_TIMESTAMP1 call",
+                                  42, 31415);
+    TRACE_COUNTER_WITH_TIMESTAMP2("all", "TRACE_COUNTER_WITH_TIMESTAMP2 call",
+                                  42, "a", 30000, "b", 1415);
+
     TRACE_COUNTER_ID1("all", "TRACE_COUNTER_ID1 call", 0x319009, 31415);
     TRACE_COUNTER_ID2("all", "TRACE_COUNTER_ID2 call", 0x319009,
                       "a", 30000, "b", 1415);
@@ -655,6 +660,39 @@ void ValidateAllTraceMacrosCreatedData(const ListValue& trace_parsed) {
     EXPECT_EQ(1415, value);
   }
 
+  EXPECT_FIND_("TRACE_COUNTER_WITH_TIMESTAMP1 call");
+  {
+    std::string ph;
+    EXPECT_TRUE((item && item->GetString("ph", &ph)));
+    EXPECT_EQ("C", ph);
+
+    int value;
+    EXPECT_TRUE((item && item->GetInteger("args.value", &value)));
+    EXPECT_EQ(31415, value);
+
+    int ts;
+    EXPECT_TRUE((item && item->GetInteger("ts", &ts)));
+    EXPECT_EQ(42, ts);
+  }
+
+  EXPECT_FIND_("TRACE_COUNTER_WITH_TIMESTAMP2 call");
+  {
+    std::string ph;
+    EXPECT_TRUE((item && item->GetString("ph", &ph)));
+    EXPECT_EQ("C", ph);
+
+    int value;
+    EXPECT_TRUE((item && item->GetInteger("args.a", &value)));
+    EXPECT_EQ(30000, value);
+
+    EXPECT_TRUE((item && item->GetInteger("args.b", &value)));
+    EXPECT_EQ(1415, value);
+
+    int ts;
+    EXPECT_TRUE((item && item->GetInteger("ts", &ts)));
+    EXPECT_EQ(42, ts);
+  }
+
   EXPECT_FIND_("TRACE_COUNTER_ID1 call");
   {
     std::string id;