Change Android activity title from JNI call

tools/viewer/sk_app/android/surface_glue_android.h

Index: tools/viewer/sk_app/android/surface_glue_android.h
diff --git a/tools/viewer/sk_app/android/surface_glue_android.h b/tools/viewer/sk_app/android/surface_glue_android.h
index 296112258e4ea5b3d92af374e90eb32e08f74a91..d9c27b2a9bcb635568c80e9c737f8e332a62f28b 100644
--- a/tools/viewer/sk_app/android/surface_glue_android.h
+++ b/tools/viewer/sk_app/android/surface_glue_android.h
@@ -37,19 +37,31 @@ struct Message {
 };
 
 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

[djsollen, 2016/05/13 14:56:27]

do we have some way to enforce this behavior?

[liyuqian, 2016/05/13 15:18:41]

One way that I can think of is to check the current thread, and throw an
exception if the current thread is not our pthread. This is currently done by
JNI: if you call these methods from another thread, JNI throws an exception
saying that you should only use the JNIEnv in the correct thread.

     ~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 setAndroidTitle(const char* title) const;

[djsollen, 2016/05/13 14:56:27]

shorten to setTitle

[liyuqian, 2016/05/13 15:18:42]

Done.

+
+    static int message_callback(int fd, int events, void* data);
+    static void* pthread_main(void*);

[djsollen, 2016/05/13 14:56:27]

I think you should be able to make these functions private.

[liyuqian, 2016/05/13 15:18:42]

Done.

+
 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;
 };
 
 }  // namespace sk_app