arc: enable Android tracing from chrome://tracing in dev mode

content/browser/tracing/tracing_controller_impl.cc

 // Copyright (c) 2013 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 "content/browser/tracing/tracing_controller_impl.h"
 
+#include <algorithm>
+#include <memory>
+#include <utility>
+
 #include "base/bind.h"
 #include "base/cpu.h"
 #include "base/files/file_util.h"
 #include "base/guid.h"
 #include "base/json/string_escape.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted_memory.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/sys_info.h"
 #include "base/threading/thread_task_runner_handle.h"
@@ skipping 21 matching lines @@
 #define ENABLE_POWER_TRACING
 #endif
 
 #if defined(ENABLE_POWER_TRACING)
 #include "content/browser/tracing/power_tracing_agent.h"
 #endif
 
 #if defined(OS_CHROMEOS)
 #include "chromeos/dbus/dbus_thread_manager.h"
 #include "chromeos/dbus/debug_daemon_client.h"
+#include "chromeos/trace/arc_trace_agent.h"
 #endif
 
 #if defined(OS_WIN)
 #include "content/browser/tracing/etw_tracing_agent_win.h"
 #endif
 
 using base::trace_event::TraceLog;
 using base::trace_event::TraceConfig;
 
 namespace content {
 
 namespace {
 
 base::LazyInstance<TracingControllerImpl>::Leaky g_controller =
     LAZY_INSTANCE_INITIALIZER;
 
 const char kChromeTracingAgentName[] = "chrome";
 const char kETWTracingAgentName[] = "etw";
+const char kArcTracingAgentName[] = "arc";
 const char kChromeTraceLabel[] = "traceEvents";
 
 const int kStartTracingTimeoutSeconds = 30;
 const int kIssueClockSyncTimeoutSeconds = 30;
 const int kStopTracingRetryTimeMilliseconds = 100;
 
 std::string GetNetworkTypeString() {
   switch (net::NetworkChangeNotifier::GetConnectionType()) {
     case net::NetworkChangeNotifier::CONNECTION_ETHERNET:
       return "Ethernet";
@@ skipping 215 matching lines @@
     }
 #elif defined(OS_WIN)
     EtwTracingAgent::GetInstance()->StartAgentTracing(
         trace_config,
         base::Bind(&TracingControllerImpl::OnStartAgentTracingAcked,
                    base::Unretained(this)));
     ++pending_start_tracing_ack_count_;
 #endif
   }
 
+#if defined(OS_CHROMEOS)
+  auto* arc_trace_agent = chromeos::ArcTraceAgent::GetInstance();
+  if (arc_trace_agent) {

[Luis Héctor Chávez, 2017/02/16 16:45:11]

Why would |arc_trace_agent| be nullptr? Maybe you should follow the pattern that
the EtwTracingAgent uses. Same in L584.

[Earl Ou, 2017/02/17 02:12:59]

Done.

+    arc_trace_agent->StartAgentTracing(
+        trace_config,
+        base::Bind(&TracingControllerImpl::OnStartAgentTracingAcked,
+                   base::Unretained(this)));
+    ++pending_start_tracing_ack_count_;
+  }
+#endif
+
   // TraceLog may have been enabled in startup tracing before threads are ready.
   if (TraceLog::GetInstance()->IsEnabled())
     return true;
 
   StartAgentTracing(trace_config,
                     base::Bind(&TracingControllerImpl::OnStartAgentTracingAcked,
                                base::Unretained(this)));
   ++pending_start_tracing_ack_count_;
 
   // Set a deadline to ensure all agents ack within a reasonable time frame.
@@ skipping 245 matching lines @@
 void TracingControllerImpl::AddTracingAgent(const std::string& agent_name) {
 #if defined(OS_CHROMEOS)
   auto* debug_daemon =
       chromeos::DBusThreadManager::Get()->GetDebugDaemonClient();
   if (agent_name == debug_daemon->GetTracingAgentName()) {
     additional_tracing_agents_.push_back(debug_daemon);
     debug_daemon->SetStopAgentTracingTaskRunner(
         BrowserThread::GetBlockingPool());
     return;
   }
+
+  auto* arc_trace_agent = chromeos::ArcTraceAgent::GetInstance();
+  if (arc_trace_agent && agent_name == arc_trace_agent->GetTracingAgentName()) {
+    additional_tracing_agents_.push_back(arc_trace_agent);
+    return;
+  }
 #elif defined(OS_WIN)
   auto* etw_agent = EtwTracingAgent::GetInstance();
   if (agent_name == etw_agent->GetTracingAgentName()) {
     additional_tracing_agents_.push_back(etw_agent);
     return;
   }
 #endif
 
 #if defined(ENABLE_POWER_TRACING)
   auto* power_agent = PowerTracingAgent::GetInstance();
@@ skipping 92 matching lines @@
   if (trace_data_sink_.get() && events_str_ptr &&
       !events_str_ptr->data().empty()) {
     std::string json_string;
     if (agent_name == kETWTracingAgentName) {
       // The Windows kernel events are kept into a JSON format stored as string
       // and must not be escaped.
       json_string = events_str_ptr->data();
     } else {
       json_string = base::GetQuotedJSONString(events_str_ptr->data());
     }
-    trace_data_sink_->AddAgentTrace(events_label, json_string);
+
+    // ARC tracing data is obtained via systrace. Ignore the empty data here.
+    if (agent_name != kArcTracingAgentName) {
+      trace_data_sink_->AddAgentTrace(events_label, json_string);
+    }
   }
   std::vector<std::string> category_groups;
   OnStopTracingAcked(NULL, category_groups);
 }
 
 void TracingControllerImpl::OnTraceDataCollected(
     const scoped_refptr<base::RefCountedString>& events_str_ptr) {
   // OnTraceDataCollected may be called from any browser thread, either by the
   // local event trace system or from child processes via TraceMessageFilter.
   if (!BrowserThread::CurrentlyOn(BrowserThread::UI)) {
@@ skipping 134 matching lines @@
 void TracingControllerImpl::RecordClockSyncMarker(
     const std::string& sync_id,
     const RecordClockSyncMarkerCallback& callback) {
   DCHECK(SupportsExplicitClockSync());
 
   TRACE_EVENT_CLOCK_SYNC_RECEIVER(sync_id);
 }
 
 void TracingControllerImpl::IssueClockSyncMarker() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
-  DCHECK(pending_clock_sync_ack_count_ == 0);
+  DCHECK_EQ(0, pending_clock_sync_ack_count_);
 
   for (auto* it : additional_tracing_agents_) {
     if (it->SupportsExplicitClockSync()) {
       it->RecordClockSyncMarker(
           base::GenerateGUID(),
           base::Bind(&TracingControllerImpl::OnClockSyncMarkerRecordedByAgent,
                      base::Unretained(this)));
       pending_clock_sync_ack_count_++;
     }
   }
@@ skipping 19 matching lines @@
   // success indicator instead of having to rely on sentinel issue_ts and
   // issue_end_ts values to signal failure.
   if (!(issue_ts == base::TimeTicks() || issue_end_ts == base::TimeTicks()))
     TRACE_EVENT_CLOCK_SYNC_ISSUER(sync_id, issue_ts, issue_end_ts);
 
   // Timer is not running means that clock sync already timed out.
   if (!clock_sync_timer_.IsRunning())
     return;
 
   // Stop tracing only if all agents report back.
-  if(--pending_clock_sync_ack_count_ == 0) {
+  if (--pending_clock_sync_ack_count_ == 0) {
     clock_sync_timer_.Stop();
     StopTracingAfterClockSync();
   }
 }
 
 void TracingControllerImpl::AddFilteredMetadata(
     TracingController::TraceDataSink* sink,
     std::unique_ptr<base::DictionaryValue> metadata,
     const MetadataFilterPredicate& filter) {
   if (filter.is_null()) {
@@ skipping 177 matching lines @@
   // Schedule the next queued dump (if applicable).
   if (!queued_memory_dump_requests_.empty()) {
     BrowserThread::PostTask(
         BrowserThread::UI, FROM_HERE,
         base::Bind(&TracingControllerImpl::PerformNextQueuedGlobalMemoryDump,
                    base::Unretained(this)));
   }
 }
 
 }  // namespace content