Ensure we have a GL context before deleting View layers

Bug #7391098

The existing code was doing a make current to guarantee we have a
current context. This can however fail when the surface is destroyed
which could lead to GL calls without an EGL context, and therefore
potential leaks. This change fixes the issue by using a technique
found in HardwareRenderer.destroyHardwareResources(). If the surface
is not available then we use a special 1x1 pbuffer as a way to get
a valid context.

Change-Id: I716d3799bf90120d793d76e90a83956837ecd491

Author: Romain Guy

core/java/android/view/HardwareRenderer.java

@@ -1525,30 +1525,6 @@ void setSurfaceTexture(HardwareLayer layer, SurfaceTexture surfaceTexture) {
             ((GLES20TextureLayer) layer).setSurfaceTexture(surfaceTexture);
         }
 
-        @Override
-        void destroyLayers(View view) {
-            if (view != null && isEnabled() && checkCurrent() != SURFACE_STATE_ERROR) {
-                if (mCanvas != null) {
-                    mCanvas.clearLayerUpdates();
-                }
-                destroyHardwareLayer(view);
-                GLES20Canvas.flushCaches(GLES20Canvas.FLUSH_CACHES_LAYERS);
-            }
-        }
-
-        private static void destroyHardwareLayer(View view) {
-            view.destroyLayer(true);
-
-            if (view instanceof ViewGroup) {
-                ViewGroup group = (ViewGroup) view;
-
-                int count = group.getChildCount();
-                for (int i = 0; i < count; i++) {
-                    destroyHardwareLayer(group.getChildAt(i));
-                }
-            }
-        }
-
         @Override
         boolean safelyRun(Runnable action) {
             boolean needsContext = true;
@@ -1573,6 +1549,35 @@ boolean safelyRun(Runnable action) {
             return true;
         }
 
+        @Override
+        void destroyLayers(final View view) {
+            if (view != null) {
+                safelyRun(new Runnable() {
+                    @Override
+                    public void run() {
+                        if (mCanvas != null) {
+                            mCanvas.clearLayerUpdates();
+                        }
+                        destroyHardwareLayer(view);
+                        GLES20Canvas.flushCaches(GLES20Canvas.FLUSH_CACHES_LAYERS);
+                    }
+                });
+            }
+        }
+
+        private static void destroyHardwareLayer(View view) {
+            view.destroyLayer(true);
+
+            if (view instanceof ViewGroup) {
+                ViewGroup group = (ViewGroup) view;
+
+                int count = group.getChildCount();
+                for (int i = 0; i < count; i++) {
+                    destroyHardwareLayer(group.getChildAt(i));
+                }
+            }
+        }
+
         @Override
         void destroyHardwareResources(final View view) {
             if (view != null) {