Revert of Port over the mojo tracing service from the mojo repo. (patchset #3 id:40001 of https://codereview.chromium.org/1415843003/ )

Reason for revert:
Seems to have broken at least the Win x64 gn build

http://build.chromium.org/p/chromium.win/builders/Win%20x64%20GN/builds/7438

Original issue's description:
> Port over the mojo tracing service from the mojo repo.
>
> When we unforked from the mojo repo, we got the tracing service in a
> state where it didn't reliably collect reports from different
> processes. This ports all the startup time tracking changes we added to
> the tracing application onto the mojo repo's tracing service.
>
> With this change, mandoline traces go from totally useless to merely
> missing most of the data.
>
> BUG=534895
> R=msw@chromium.org
> TBR=ben@chromium.org
>
> Committed: https://crrev.com/83e47b933a49ee7ba011a862eb706a0d25ec1624
> Cr-Commit-Position: refs/heads/master@{#355197}

TBR=msw@chromium.org,ben@chromium.org,erg@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=534895

Review URL: https://codereview.chromium.org/1408323005

Cr-Commit-Position: refs/heads/master@{#355222}

2 files changed, 76 insertions, 14 deletions

diff --git a/mandoline/app/desktop/launcher_process.cc b/mandoline/app/desktop/launcher_process.cc
index 0b28d7a..2424045 100644
--- a/mandoline/app/desktop/launcher_process.cc
+++ b/mandoline/app/desktop/launcher_process.cc
@@ -21,34 +21,97 @@
 #include "mandoline/app/desktop/launcher_process.h"
 #include "mojo/runner/context.h"
 #include "mojo/runner/switches.h"
-#include "mojo/runner/tracer.h"
 
 namespace mandoline {
+namespace {
+
+// Whether we're currently tracing.
+bool g_tracing = false;
+
+// Number of tracing blocks written.
+uint32_t g_blocks = 0;
+
+// Trace file, if open.
+FILE* g_trace_file = nullptr;
+
+void WriteTraceDataCollected(
+    base::WaitableEvent* event,
+    const scoped_refptr<base::RefCountedString>& events_str,
+    bool has_more_events) {
+  if (g_blocks) {
+    fwrite(",", 1, 1, g_trace_file);
+  }
+
+  ++g_blocks;
+  fwrite(events_str->data().c_str(), 1, events_str->data().length(),
+         g_trace_file);
+  if (!has_more_events) {
+    static const char kEnd[] = "]}";
+    fwrite(kEnd, 1, strlen(kEnd), g_trace_file);
+    PCHECK(fclose(g_trace_file) == 0);
+    g_trace_file = nullptr;
+    event->Signal();
+  }
+}
+
+void EndTraceAndFlush(base::WaitableEvent* event) {
+  g_trace_file = fopen("mojo_shell.trace", "w+");
+  PCHECK(g_trace_file);
+  static const char kStart[] = "{\"traceEvents\":[";
+  fwrite(kStart, 1, strlen(kStart), g_trace_file);
+  base::trace_event::TraceLog::GetInstance()->SetDisabled();
+  base::trace_event::TraceLog::GetInstance()->Flush(
+      base::Bind(&WriteTraceDataCollected, base::Unretained(event)));
+}
+
+void StopTracingAndFlushToDisk() {
+  g_tracing = false;
+  base::trace_event::TraceLog::GetInstance()->SetDisabled();
+  base::WaitableEvent flush_complete_event(false, false);
+  // TraceLog::Flush requires a message loop but we've already shut ours down.
+  // Spin up a new thread to flush things out.
+  base::Thread flush_thread("mojo_shell_trace_event_flush");
+  flush_thread.Start();
+  flush_thread.message_loop()->PostTask(
+      FROM_HERE,
+      base::Bind(EndTraceAndFlush, base::Unretained(&flush_complete_event)));
+  flush_complete_event.Wait();
+}
+
+}  // namespace
 
 int LauncherProcessMain(int argc, char** argv) {
-  mojo::runner::Tracer tracer;
   const base::CommandLine& command_line =
       *base::CommandLine::ForCurrentProcess();
-
-  bool trace_startup = command_line.HasSwitch(switches::kTraceStartup);
-  if (trace_startup) {
-    tracer.Start(
+  if (command_line.HasSwitch(switches::kTraceStartup)) {
+    g_tracing = true;
+    base::trace_event::TraceConfig trace_config(
         command_line.GetSwitchValueASCII(switches::kTraceStartup),
-        command_line.GetSwitchValueASCII(switches::kTraceStartupDuration),
-        "mandoline.trace");
+        base::trace_event::RECORD_UNTIL_FULL);
+    base::trace_event::TraceLog::GetInstance()->SetEnabled(
+        trace_config, base::trace_event::TraceLog::RECORDING_MODE);
+  } else if (tracing::TraceConfigFile::GetInstance()->IsEnabled()) {
+    g_tracing = true;
+    base::trace_event::TraceLog::GetInstance()->SetEnabled(
+        tracing::TraceConfigFile::GetInstance()->GetTraceConfig(),
+        base::trace_event::TraceLog::RECORDING_MODE);
   }
 
   // We want the runner::Context to outlive the MessageLoop so that pipes are
   // all gracefully closed / error-out before we try to shut the Context down.
   base::FilePath shell_dir;
   PathService::Get(base::DIR_MODULE, &shell_dir);
-  mojo::runner::Context shell_context(shell_dir, &tracer);
+  mojo::runner::Context shell_context(shell_dir);
   {
     base::MessageLoop message_loop;
-    tracer.DidCreateMessageLoop();
     if (!shell_context.Init()) {
       return 0;
     }
+    if (g_tracing) {
+      message_loop.PostDelayedTask(FROM_HERE,
+                                   base::Bind(StopTracingAndFlushToDisk),
+                                   base::TimeDelta::FromSeconds(5));
+    }
 
     message_loop.PostTask(FROM_HERE,
                           base::Bind(&mojo::runner::Context::Run,
@@ -60,9 +123,8 @@ int LauncherProcessMain(int argc, char** argv) {
     shell_context.Shutdown();
   }
 
-  if (trace_startup)
-    tracer.StopAndFlushToFile();
-
+  if (g_tracing)
+    StopTracingAndFlushToDisk();
   return 0;
 }
 
diff --git a/mandoline/services/core_services/BUILD.gn b/mandoline/services/core_services/BUILD.gn
index f3b6ed7..9edb1f1 100644
--- a/mandoline/services/core_services/BUILD.gn
+++ b/mandoline/services/core_services/BUILD.gn
@@ -48,10 +48,10 @@ source_set("sources") {
     "//components/filesystem:lib",
     "//components/web_view:lib",
     "//mojo/application/public/cpp",
+    "//mojo/common:tracing_impl",
     "//mojo/logging",
     "//mojo/message_pump",
     "//mojo/services/tracing:lib",
-    "//mojo/services/tracing/public/cpp",
     "//third_party/icu",
     "//third_party/mojo/src/mojo/public/cpp/bindings",
     "//url",