TRACING: Enable java tracing from native also

Currently java traces are enabled in Java only when tracing
that is triggered from an Android intent. This flips it
around so we always notify Java to start tracing, no
matter how tracing is enabled.

The case that wasn't working in this case is the 'dev tools
tracing handler' which is how tracing is enabled for
telemetry.

BUG=None

Review URL: https://codereview.chromium.org/237853005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@265763 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 20 insertions, 2 deletions

diff --git a/base/android/trace_event_binding.cc b/base/android/trace_event_binding.cc
index f802f3d..e261411 100644
--- a/base/android/trace_event_binding.cc
+++ b/base/android/trace_event_binding.cc
@@ -9,6 +9,7 @@
 #include <set>
 
 #include "base/debug/trace_event.h"
+#include "base/debug/trace_event_impl.h"
 #include "base/lazy_instance.h"
 #include "jni/TraceEvent_jni.h"
 
@@ -54,10 +55,27 @@ class TraceEventDataConverter {
   DISALLOW_COPY_AND_ASSIGN(TraceEventDataConverter);
 };
 
+class TraceEnabledObserver : public debug::TraceLog::EnabledStateObserver {
+  public:
+    virtual void OnTraceLogEnabled() OVERRIDE {
+      JNIEnv* env = base::android::AttachCurrentThread();
+      base::android::Java_TraceEvent_setEnabled(env, true);
+    }
+    virtual void OnTraceLogDisabled() OVERRIDE {
+      JNIEnv* env = base::android::AttachCurrentThread();
+      base::android::Java_TraceEvent_setEnabled(env, false);
+    }
+};
+
+base::LazyInstance<TraceEnabledObserver>::Leaky g_trace_enabled_state_observer_;
+
 }  // namespace
 
-static jboolean TraceEnabled(JNIEnv* env, jclass clazz) {
-  return base::debug::TraceLog::GetInstance()->IsEnabled();
+static void RegisterEnabledObserver(JNIEnv* env, jclass clazz) {
+  bool enabled = debug::TraceLog::GetInstance()->IsEnabled();
+  base::android::Java_TraceEvent_setEnabled(env, enabled);
+  debug::TraceLog::GetInstance()->AddEnabledStateObserver(
+      g_trace_enabled_state_observer_.Pointer());
 }
 
 static void StartATrace(JNIEnv* env, jclass clazz) {