Execute callbacks in proper threads

support/android/apk/servoview/src/main/java/com/mozilla/servoview/Servo.java

@@ -126,15 +126,17 @@ public void wakeup() {
         }
 
         public void flush() {
-            mRunCallback.inUIThread(() -> mGfxCb.flushGLBuffers());
+            // Up to the callback to execute this in the right thread
+            mGfxCb.flushGLBuffers();
         }
 
         public void makeCurrent() {
-            mRunCallback.inUIThread(() -> mGfxCb.makeCurrent());
+            // Up to the callback to execute this in the right thread
+            mGfxCb.makeCurrent();
         }
 
         public void onAnimatingChanged(boolean animating) {
-            mRunCallback.inUIThread(() -> mGfxCb.animationStateChanged(animating));
+            mRunCallback.inGLThread(() -> mGfxCb.animationStateChanged(animating));
         }
 
         public void onLoadStarted() {
@@ -165,7 +167,7 @@ public void onHistoryChanged(boolean canGoBack, boolean canGoForward) {
                 stream.close();
                 return bytes;
             } catch (IOException e) {
-                Log.e(LOGTAG, e.getMessage());
+                Log.e(LOGTAG, "readfile error: " + e.getMessage());
                 return null;
             }
         }

support/android/apk/servoview/src/main/java/com/mozilla/servoview/ServoSurface.java

@@ -28,6 +28,7 @@
 import static android.opengl.EGL14.EGL_OPENGL_ES2_BIT;
 
 public class ServoSurface {
+    private static final String LOGTAG = "ServoSurface";
     private final GLThread mGLThread;
     private final Handler mMainLooperHandler;
     private Handler mGLLooperHandler;
@@ -113,8 +114,6 @@ public void loadUri(Uri uri) {
     }
 
     static class GLSurface implements GfxCallbacks {
-        private static final String LOGTAG = "ServoSurface";
-
         private EGLConfig[] mEGLConfigs;
         private EGLDisplay mEglDisplay;
         private EGLContext mEglContext;
@@ -160,7 +159,7 @@ public void loadUri(Uri uri) {
                 throw new RuntimeException("Error: createWindowSurface() Failed " + GLUtils.getEGLErrorString(glError));
             }
 
-            flushGLBuffers();
+            makeCurrent();
         }
 
 
@@ -205,7 +204,9 @@ public void handleMessage(Message msg) {
                 }
             };
 
-            mServo = new Servo(this, surface, mClient, mActivity, mServoArgs, uri, mWidth, mHeight, showLogs);
+            inUIThread(() -> {
+              mServo = new Servo(this, surface, mClient, mActivity, mServoArgs, uri, mWidth, mHeight, showLogs);
+            });
 
             Looper.loop();
         }

support/android/apk/servoview/src/main/java/com/mozilla/servoview/ServoView.java

@@ -95,7 +95,9 @@ public void loadUri(Uri uri) {
     }
 
     public void flushGLBuffers() {
+      inUIThread(() -> {
         requestRender();
+      });
     }
 
     // Scroll and click