[android] Set thread name properly

platform/android/platform.gyp

@@ -31,7 +31,7 @@
         'src/log_android.cpp',
         'src/http_file_source.cpp',
         'src/asset_file_source.cpp',
-        '../default/thread.cpp',
+        'src/thread.cpp',
         '../default/string_stdlib.cpp',
         '../default/image.cpp',
         '../default/png_reader.cpp',

platform/android/src/run_loop.cpp

@@ -1,5 +1,6 @@
 #include "run_loop_impl.hpp"
 
+#include <mbgl/platform/platform.hpp>
 #include <mbgl/util/thread_context.hpp>
 #include <mbgl/util/thread_local.hpp>
 #include <mbgl/util/timer.hpp>
@@ -75,7 +76,7 @@ private:
 
 RunLoop::Impl::Impl(RunLoop* runLoop_, RunLoop::Type type) : runLoop(runLoop_) {
     using namespace mbgl::android;
-    detach = attach_jni_thread(theJVM, &env, "");
+    detach = attach_jni_thread(theJVM, &env, platform::getCurrentThreadName());
 
     loop = ALooper_prepare(0);
     assert(loop);

platform/android/src/thread.cpp

@@ -0,0 +1,37 @@
+#include <mbgl/platform/log.hpp>
+#include <mbgl/platform/platform.hpp>
+
+#include <sys/prctl.h>
+#include <sys/resource.h>
+
+// Implementation based on Chromium's platform_thread_android.cc.
+
+namespace mbgl {
+namespace platform {
+
+std::string getCurrentThreadName() {
+    char name[32] = "unknown";
+
+    if (prctl(PR_GET_NAME, name) == -1) {
+        Log::Warning(Event::General, "Couldn't get thread name");
+    }
+
+    return name;
+}
+
+void setCurrentThreadName(const std::string& name) {
+    if (prctl(PR_SET_NAME, name.c_str()) == -1) {
+        Log::Warning(Event::General, "Couldn't set thread name");
+    }
+}
+
+void makeThreadLowPriority() {
+    // ANDROID_PRIORITY_LOWEST = 19
+    //
+    // Supposedly would set the priority for the whole process, but
+    // on Linux/Android it only sets for the current thread.
+    setpriority(PRIO_PROCESS, 0, 19);
+}
+
+} // namespace platform
+} // namespace mbgl