Use FileNetLogObserver in Cast.

This replaces use of the deprecated WriteToFileNetLogObserver.
It has the advantage of moving file I/O off the calling thread.

Bug: 716570
Change-Id: Idac0cec3d1eb59fedc1793e2f60f9244d0324789
Reviewed-on: https://chromium-review.googlesource.com/564074Reviewed-by: Matt Menke <mmenke@chromium.org>
Reviewed-by: Luke Halliwell <halliwell@chromium.org>
Commit-Queue: Eric Roman <eroman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#485339}

chromecast/browser/cast_net_log.cc

@@ -8,14 +8,15 @@
 
 #include <utility>
 
+#include "base/bind.h"
 #include "base/command_line.h"
 #include "base/files/file_path.h"
 #include "base/files/scoped_file.h"
 #include "base/memory/ptr_util.h"
 #include "base/values.h"
 #include "content/public/common/content_switches.h"
+#include "net/log/file_net_log_observer.h"
 #include "net/log/net_log_util.h"
-#include "net/log/write_to_file_net_log_observer.h"
 
 namespace chromecast {
 
@@ -41,39 +42,25 @@ std::unique_ptr<base::DictionaryValue> GetShellConstants() {
 }  // namespace
 
 CastNetLog::CastNetLog() {
-  // TODO(derekjchow): This code is virtually identical to ShellNetLog which is
-  //     nearly identical to code in ChromeNetLog. Consider merging the code.
   const base::CommandLine* command_line =
       base::CommandLine::ForCurrentProcess();
 
   if (command_line->HasSwitch(switches::kLogNetLog)) {
     base::FilePath log_path =
         command_line->GetSwitchValuePath(switches::kLogNetLog);
-    // Much like logging.h, bypass threading restrictions by using fopen
-    // directly.  Have to write on a thread that's shutdown to handle events on
-    // shutdown properly, and posting events to another thread as they occur
-    // would result in an unbounded buffer size, so not much can be gained by
-    // doing this on another thread.  It's only used when debugging, so
-    // performance is not a big concern.
-    base::ScopedFILE file;
-    file.reset(fopen(log_path.value().c_str(), "w"));
-
-    if (!file) {
-      LOG(ERROR) << "Could not open file " << log_path.value()
-                 << " for net logging";
-    } else {
-      std::unique_ptr<base::Value> constants(GetShellConstants());
-      write_to_file_observer_.reset(new net::WriteToFileNetLogObserver());
-      write_to_file_observer_->StartObserving(this, std::move(file),
-                                              constants.get(), nullptr);
-    }
+    net::NetLogCaptureMode capture_mode = net::NetLogCaptureMode::Default();
+
+    file_net_log_observer_ =
+        net::FileNetLogObserver::CreateUnbounded(log_path, GetShellConstants());
+
+    file_net_log_observer_->StartObserving(this, capture_mode);
   }
 }
 
 CastNetLog::~CastNetLog() {
   // Remove the observer we own before we're destroyed.
-  if (write_to_file_observer_)
-    write_to_file_observer_->StopObserving(nullptr);
+  if (file_net_log_observer_)
+    file_net_log_observer_->StopObserving(nullptr, base::OnceClosure());
 }
 
 }  // namespace chromecast

chromecast/browser/cast_net_log.h

@@ -9,7 +9,11 @@
 #include <string>
 
 #include "base/macros.h"
-#include "net/log/write_to_file_net_log_observer.h"
+#include "net/log/net_log.h"
+
+namespace net {
+class FileNetLogObserver;
+}
 
 namespace chromecast {
 
@@ -19,7 +23,7 @@ class CastNetLog : public net::NetLog {
   ~CastNetLog() override;
 
  private:
-  std::unique_ptr<net::WriteToFileNetLogObserver> write_to_file_observer_;
+  std::unique_ptr<net::FileNetLogObserver> file_net_log_observer_;
 
   DISALLOW_COPY_AND_ASSIGN(CastNetLog);
 };