Bug 1170061 - ClearOnShutdown for hwcomposer, r=sotaro

Call ClearOnShutdown while creaing HwcComposer2D object.

widget/gonk/HwcComposer2D.cpp

@@ -25,6 +25,7 @@
 #include "HwcComposer2D.h"
 #include "LayerScope.h"
 #include "Units.h"
+#include "mozilla/ClearOnShutdown.h"
 #include "mozilla/layers/CompositorParent.h"
 #include "mozilla/layers/LayerManagerComposite.h"
 #include "mozilla/layers/PLayerTransaction.h"
@@ -130,8 +131,24 @@ HwcComposer2D*
 HwcComposer2D::GetInstance()
 {
     if (!sInstance) {
+#ifdef HWC_DEBUG
+        // Make sure only create once
+        static int timesCreated = 0;
+        ++timesCreated;
+        MOZ_ASSERT(timesCreated == 1);
+#endif
         LOGI("Creating new instance");
         sInstance = new HwcComposer2D();
+
+        // If anyone uses the compositor thread to create HwcComposer2D,
+        // we just skip this function.
+        // If ClearOnShutdown() can handle objects in other threads
+        // in the future, we can remove this check.
+        if (NS_IsMainThread()) {
+            // If we create HwcComposer2D by the main thread, we can use
+            // ClearOnShutdown() to make sure it will be nullified properly.
+            ClearOnShutdown(&sInstance);
+        }
     }
     return sInstance;
 }
@@ -206,6 +223,7 @@ public:
         } else {
             screenManager->RemoveScreen(mType);
         }
+        return NS_OK;
     }
 private:
     GonkDisplay::DisplayType mType;

widget/gonk/nsWindow.cpp

@@ -87,7 +87,7 @@ nsWindow::nsWindow()
 nsWindow::~nsWindow()
 {
     if (mScreen->IsPrimaryScreen()) {
-        HwcComposer2D::GetInstance()->SetCompositorParent(nullptr);
+        mComposer2D->SetCompositorParent(nullptr);
     }
 }
 
@@ -356,6 +356,8 @@ nsWindow::Create(nsIWidget *aParent,
         mBounds = mScreen->GetRect();
     }
 
+    mComposer2D = HwcComposer2D::GetInstance();
+
     if (!IS_TOPLEVEL()) {
         return NS_OK;
     }
@@ -754,7 +756,7 @@ nsWindow::GetLayerManager(PLayerTransactionChild* aShadowManager,
 
     CreateCompositor();
     if (mCompositorParent && mScreen->IsPrimaryScreen()) {
-        HwcComposer2D::GetInstance()->SetCompositorParent(mCompositorParent);
+        mComposer2D->SetCompositorParent(mCompositorParent);
     }
     MOZ_ASSERT(mLayerManager);
     return mLayerManager;
@@ -831,5 +833,5 @@ nsWindow::GetComposer2D()
         return nullptr;
     }
 
-    return HwcComposer2D::GetInstance();
+    return mComposer2D;
 }

widget/gonk/nsWindow.h

@@ -29,6 +29,10 @@ struct InputContext;
 struct InputContextAction;
 }
 
+namespace mozilla {
+class HwcComposer2D;
+}
+
 class nsScreenGonk;
 
 class nsWindow : public nsBaseWidget
@@ -159,6 +163,8 @@ private:
     nsAutoPtr<mozilla::MultiTouchInput> mSynthesizedTouchInput;
 
     nsRefPtr<nsScreenGonk> mScreen;
+
+    nsRefPtr<mozilla::HwcComposer2D> mComposer2D;
 };
 
 #endif /* nsWindow_h */