Bug 1453501 - Immediately create Compositor on Android r=jchen,rbarker

Currently we don't create the Compositor until we have a valid surface
to render into. This causes a race that can result in us not being able
to display anything at all once a surface is provided and the compositor
is started. It seems the easiest thing to do right now is to avoid the
race by starting the Compositor immediately.

MozReview-Commit-ID: HkdVL3LBNZB

mobile/android/geckoview/src/main/java/org/mozilla/gecko/gfx/LayerSession.java

@@ -82,10 +82,6 @@ public class LayerSession {
         @WrapForJNI(calledFrom = "ui", dispatchTo = "gecko")
         public native void onBoundsChanged(int left, int top, int width, int height);
 
-        // Gecko thread creates compositor; blocks UI thread.
-        @WrapForJNI(calledFrom = "ui", dispatchTo = "proxy")
-        public native void createCompositor(int width, int height, Object surface);
-
         // Gecko thread pauses compositor; blocks UI thread.
         @WrapForJNI(calledFrom = "ui", dispatchTo = "current")
         public native void syncPauseCompositor();
@@ -163,7 +159,6 @@ public class LayerSession {
     private CompositorController mController;
 
     private boolean mAttachedCompositor;
-    private boolean mCalledCreateCompositor;
     private boolean mCompositorReady;
     private Surface mSurface;
 
@@ -361,6 +356,8 @@ public class LayerSession {
             // Leave mSurface alone because we'll need it later for onCompositorReady.
             onSurfaceChanged(mSurface, mWidth, mHeight);
         }
+
+        mCompositor.sendToolbarAnimatorMessage(IS_COMPOSITOR_CONTROLLER_OPEN);
     }
 
     /* package */ void onCompositorDetached() {
@@ -373,7 +370,6 @@ public class LayerSession {
         }
 
         mAttachedCompositor = false;
-        mCalledCreateCompositor = false;
         mCompositorReady = false;
     }
 
@@ -552,12 +548,6 @@ public class LayerSession {
             return;
         }
 
-        if (mAttachedCompositor && !mCalledCreateCompositor) {
-            mCompositor.createCompositor(width, height, surface);
-            mCompositor.sendToolbarAnimatorMessage(IS_COMPOSITOR_CONTROLLER_OPEN);
-            mCalledCreateCompositor = true;
-        }
-
         // We have a valid surface but we're not attached or the compositor
         // is not ready; save the surface for later when we're ready.
         mSurface = surface;

widget/android/nsWindow.cpp

@@ -823,19 +823,6 @@ class nsWindow::LayerViewSupport final
 public:
     typedef LayerSession::Compositor::Natives<LayerViewSupport> Base;
 
-    template<class Functor>
-    static void OnNativeCall(Functor&& aCall)
-    {
-        if (aCall.IsTarget(&LayerViewSupport::CreateCompositor)) {
-            // This call is blocking.
-            nsAppShell::SyncRunEvent(nsAppShell::LambdaEvent<Functor>(
-                    mozilla::Move(aCall)), &LayerViewEvent::MakeEvent);
-            return;
-        }
-
-        MOZ_CRASH("Unexpected call");
-    }
-
     static LayerViewSupport*
     FromNative(const LayerSession::Compositor::LocalRef& instance)
     {
@@ -930,20 +917,6 @@ public:
         mWindow->Resize(aLeft, aTop, aWidth, aHeight, /* repaint */ false);
     }
 
-    void CreateCompositor(int32_t aWidth, int32_t aHeight,
-                          jni::Object::Param aSurface)
-    {
-        MOZ_ASSERT(NS_IsMainThread());
-        if (!mWindow) {
-            return; // Already shut down.
-        }
-
-        mSurface = aSurface;
-        mWindow->CreateLayerManager(aWidth, aHeight);
-
-        mCompositorPaused = false;
-    }
-
     void SyncPauseCompositor()
     {
         MOZ_ASSERT(AndroidBridge::IsJavaUiThread());
@@ -1423,6 +1396,14 @@ nsWindow::Create(nsIWidget* aParent,
         mParent = parent;
     }
 
+    // A default size of 1x1 confuses MobileViewportManager, so
+    // use 0x0 instead. This is also a little more fitting since
+    // we don't yet have a surface yet (and therefore a valid size)
+    // and 0x0 is usually recognized as invalid.
+    Resize(0, 0, false);
+
+    CreateLayerManager();
+
 #ifdef DEBUG_ANDROID_WIDGET
     DumpWindows();
 #endif
@@ -1859,7 +1840,7 @@ nsWindow::GetLayerManager(PLayerTransactionChild*, LayersBackend, LayerManagerPe
 }
 
 void
-nsWindow::CreateLayerManager(int aCompositorWidth, int aCompositorHeight)
+nsWindow::CreateLayerManager()
 {
     if (mLayerManager) {
         return;
@@ -1875,7 +1856,8 @@ nsWindow::CreateLayerManager(int aCompositorWidth, int aCompositorHeight)
     gfxPlatform::GetPlatform();
 
     if (ShouldUseOffMainThreadCompositing()) {
-        CreateCompositor(aCompositorWidth, aCompositorHeight);
+        LayoutDeviceIntRect rect = GetBounds();
+        CreateCompositor(rect.Width(), rect.Height());
         if (mLayerManager) {
             return;
         }

widget/android/nsWindow.h

@@ -341,7 +341,7 @@ protected:
     static void LogWindow(nsWindow *win, int index, int indent);
 
 private:
-    void CreateLayerManager(int aCompositorWidth, int aCompositorHeight);
+    void CreateLayerManager();
     void RedrawAll();
 
     mozilla::layers::LayersId GetRootLayerId() const;