Use CHROME_LOG_FILE environment variable for headless chrome logging

headless/lib/headless_content_main_delegate.cc

Index: headless/lib/headless_content_main_delegate.cc
diff --git a/headless/lib/headless_content_main_delegate.cc b/headless/lib/headless_content_main_delegate.cc
index 72df5a29a65a3adaa86b5a24e36bdc028f8dce92..5b4e786524342079bffd7db49f49d8d39a873383 100644
--- a/headless/lib/headless_content_main_delegate.cc
+++ b/headless/lib/headless_content_main_delegate.cc
@@ -6,6 +6,7 @@
 
 #include "base/base_switches.h"
 #include "base/command_line.h"
+#include "base/environment.h"
 #include "base/files/file_util.h"
 #include "base/lazy_instance.h"
 #include "base/path_service.h"
@@ -127,6 +128,13 @@ void HeadlessContentMainDelegate::InitLogging(
     log_path = log_filename;
   }
 
+  std::string filename;
+  std::unique_ptr<base::Environment> env(base::Environment::Create());
+  if (env->HasVar("CHROME_LOG_FILE") &&

[Sami, 2017/03/08 10:38:14]

nit: no need to call HasVar since GetVar will just return false if the variable
isn't there.

[irisu, 2017/03/08 23:56:08]

Done.

+      env->GetVar("CHROME_LOG_FILE", &filename) && !filename.empty()) {

[Sami, 2017/03/08 10:38:13]

Could you make this a named constant at the top of this file (e.g., like here:
https://cs.chromium.org/chromium/src/chrome/common/env_vars.cc?rcl=ae2ff2acd1...)

[irisu, 2017/03/08 23:56:08]

Done.

+    log_path = base::FilePath::FromUTF8Unsafe(filename);
+  }
+
   const std::string process_type =
       command_line.GetSwitchValueASCII(switches::kProcessType);