Change Android activity title from JNI call

tools/viewer/sk_app/android/surface_glue_android.h

 /*
 * Copyright 2016 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
 
 #ifndef surface_glue_android_DEFINED
 #define surface_glue_android_DEFINED
 
@@ skipping 19 matching lines @@
 struct Message {
     MessageType fType = kUndefined;
     ANativeWindow* fNativeWindow = nullptr;
     int keycode = 0;
 
     Message() {}
     Message(MessageType t) : fType(t) {}
 };
 
 struct SkiaAndroidApp {
-    int fPipes[2];  // 0 is the read message pipe, 1 is the write message pipe
     Application* fApp;
     Window* fWindow;
-    ANativeWindow* fNativeWindow;
+    jobject fAndroidApp;
 
-    SkiaAndroidApp();
+    SkiaAndroidApp(JNIEnv* env, jobject androidApp);
+
+    // This must be called in SkiaAndroidApp's own pthread because the JNIEnv is thread sensitive
     ~SkiaAndroidApp();
-    void postMessage(const Message& message);
-    void readMessage(Message* message);
+
+    void postMessage(const Message& message) const;
+    void readMessage(Message* message) const;
     void paintIfNeeded();
 
+    // This must be called in SkiaAndroidApp's own pthread because the JNIEnv is thread sensitive
+    void setTitle(const char* title) const;
 private:
     pthread_t fThread;
+    ANativeWindow* fNativeWindow;
+    int fPipes[2];  // 0 is the read message pipe, 1 is the write message pipe
+    JavaVM* fJavaVM;
+    JNIEnv* fPThreadEnv;
+
+    static int message_callback(int fd, int events, void* data);
+    static void* pthread_main(void*);
 };
 
 }  // namespace sk_app
 
 #endif