Add a basic support for Linux for utils/

* Timer and path utils are done.
* Window only implements initialize and setVisible

BUG=angleproject:892

Change-Id: I3f49b68ef9ec5be324b25e211199bac2953ae11e
Reviewed-on: https://chromium-review.googlesource.com/269520
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Corentin Wallez <cwallez@chromium.org>

util/linux/LinuxTimer.cpp

@@ -0,0 +1,46 @@
+//
+// Copyright (c) 2015 The ANGLE Project Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+
+// LinuxTimer.cpp: Implementation of a high precision timer class on Linux
+
+#include "linux/LinuxTimer.h"
+
+LinuxTimer::LinuxTimer()
+    : mRunning(false)
+{
+}
+
+void LinuxTimer::start()
+{
+    clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &mStartTime);
+    mRunning = true;
+}
+
+void LinuxTimer::stop()
+{
+    clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &mStopTime);
+    mRunning = false;
+}
+
+double LinuxTimer::getElapsedTime() const
+{
+    struct timespec endTime;
+    if (mRunning)
+    {
+        clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &endTime);
+    }
+    else
+    {
+        endTime = mStopTime;
+    }
+
+    return endTime.tv_sec + (1.0 / 1000000000) * endTime.tv_nsec;
+}
+
+Timer *CreateTimer()
+{
+    return new LinuxTimer();
+}

util/linux/LinuxTimer.h

@@ -0,0 +1,31 @@
+//
+// Copyright (c) 2015 The ANGLE Project Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+
+// LinuxTimer.h: Definition of a high precision timer class on Linux
+
+#ifndef UTIL_LINUX_TIMER_H
+#define UTIL_LINUX_TIMER_H
+
+#include <time.h>
+
+#include "Timer.h"
+
+class LinuxTimer : public Timer
+{
+  public:
+    LinuxTimer();
+
+    void start() override;
+    void stop() override;
+    double getElapsedTime() const override;
+
+  private:
+    bool mRunning;
+    struct timespec mStartTime;
+    struct timespec mStopTime;
+};
+
+#endif // UTIL_LINUX_TIMER_H

util/linux/Linux_path_utils.cpp

@@ -0,0 +1,47 @@
+//
+// Copyright (c) 2015 The ANGLE Project Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+
+// Linux_path_utils.cpp: Implementation of OS-specific path functions for Linux
+
+#include "path_utils.h"
+#include <array>
+#include <sys/stat.h>
+#include <unistd.h>
+
+std::string GetExecutablePath()
+{
+    struct stat sb;
+    if (lstat("/proc/self/exe", &sb) == -1)
+    {
+        return "";
+    }
+
+    char *path = static_cast<char*>(malloc(sb.st_size + 1));
+    if (!path)
+    {
+        return "";
+    }
+
+    ssize_t result = readlink("/proc/self/exe", path, sb.st_size);
+    if (result != sb.st_size)
+    {
+        free(path);
+        return "";
+    }
+
+    path[sb.st_size] = '\0';
+
+    std::string strPath(path);
+    free(path);
+    return strPath;
+}
+
+std::string GetExecutableDirectory()
+{
+    std::string executablePath = GetExecutablePath();
+    size_t lastPathSepLoc = executablePath.find_last_of("/");
+    return (lastPathSepLoc != std::string::npos) ? executablePath.substr(0, lastPathSepLoc) : "";
+}