Allow tracing to console everywhere.

content/renderer/render_thread_impl.cc

Index: content/renderer/render_thread_impl.cc
diff --git a/content/renderer/render_thread_impl.cc b/content/renderer/render_thread_impl.cc
index 32109c0d41ac8dfc4a4456a06aad7e015f458788..bf1352dcf572796bd7ea1b817764bb86f753c26e 100644
--- a/content/renderer/render_thread_impl.cc
+++ b/content/renderer/render_thread_impl.cc
@@ -10,6 +10,7 @@
 #include <vector>
 
 #include "base/allocator/allocator_extension.h"
+#include "base/base_switches.h"
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/lazy_instance.h"
@@ -397,6 +398,19 @@ void RenderThreadImpl::Init() {
     RegisterExtension(SkiaBenchmarkingExtension::Get());
   }
 
+  if (CommandLine::ForCurrentProcess()->HasSwitch(switches::kTraceToConsole)) {

[piman, 2013/07/03 17:42:28]

Could we move this to ChildThread, so that it applies to all processes,
including e.g. GPU or Plugin?

[Ian Vollick, 2013/07/03 18:48:03]

That's a great idea. Done.

+    std::string category_string =
+        CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
+            switches::kTraceToConsole);
+
+    if (!category_string.size())
+      category_string = "*";
+
+    base::debug::TraceLog::GetInstance()->SetEnabled(
+        base::debug::CategoryFilter(category_string),
+        base::debug::TraceLog::ECHO_TO_CONSOLE);
+  }
+
   context_lost_cb_.reset(new GpuVDAContextLostCallback());
 
   // Note that under Linux, the media library will normally already have