Modularize logd.

Separates logd body into a static library liblogd and
virtualize LogBuffer::log to be in a new interface class
LogBufferInterface. User could have different implementation.

Bug: 37756450
Test: liblog-unit-tests, logd-unit-tests and logcat-unit-tests
with (b/37791296).
Change-Id: I1504ff0e992744001b5a2e9abd45692d1318a152
diff --git a/logd/LogBufferInterface.h b/logd/LogBufferInterface.h
new file mode 100644
index 0000000..7d82b91
--- /dev/null
+++ b/logd/LogBufferInterface.h
@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 2012-2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _LOGD_LOG_BUFFER_INTERFACE_H__
+#define _LOGD_LOG_BUFFER_INTERFACE_H__
+
+#include <sys/types.h>
+
+#include <android-base/macros.h>
+#include <log/log_id.h>
+#include <log/log_time.h>
+
+// Abstract interface that handles log when log available.
+class LogBufferInterface {
+   public:
+    LogBufferInterface();
+    virtual ~LogBufferInterface();
+    // Handles a log entry when available in LogListener.
+    // Returns the size of the handled log message.
+    virtual int log(log_id_t log_id, log_time realtime, uid_t uid, pid_t pid,
+                    pid_t tid, const char* msg, unsigned short len) = 0;
+
+   private:
+    DISALLOW_COPY_AND_ASSIGN(LogBufferInterface);
+};
+
+#endif  // _LOGD_LOG_BUFFER_INTERFACE_H__