WebGL: Don't destroy mailbox textures in the destructor until they're released.

Source/platform/graphics/gpu/DrawingBuffer.cpp

Index: Source/platform/graphics/gpu/DrawingBuffer.cpp
diff --git a/Source/platform/graphics/gpu/DrawingBuffer.cpp b/Source/platform/graphics/gpu/DrawingBuffer.cpp
index 5c470a7d577c0d7145c986c41388acf0ab321eee..cd215dc791f5bd89c5c3ac86b7b4ff02e26ff6a0 100644
--- a/Source/platform/graphics/gpu/DrawingBuffer.cpp
+++ b/Source/platform/graphics/gpu/DrawingBuffer.cpp
@@ -77,10 +77,9 @@ private:
     Platform3DObject m_oldTextureUnitZeroId;
 };
 
-PassRefPtr<DrawingBuffer> DrawingBuffer::create(blink::WebGraphicsContext3D* context, const IntSize& size, PreserveDrawingBuffer preserve, PassRefPtr<ContextEvictionManager> contextEvictionManager)
+PassRefPtr<DrawingBuffer> DrawingBuffer::create(PassOwnPtr<blink::WebGraphicsContext3D> context, const IntSize& size, PreserveDrawingBuffer preserve, PassRefPtr<ContextEvictionManager> contextEvictionManager)
 {
-    ASSERT(context);
-    Extensions3DUtil extensionsUtil(context);
+    Extensions3DUtil extensionsUtil(context.get());
     bool multisampleSupported = extensionsUtil.supportsExtension("GL_CHROMIUM_framebuffer_multisample")
         && extensionsUtil.supportsExtension("GL_OES_rgb8_rgba8");
     if (multisampleSupported) {
@@ -97,7 +96,7 @@ PassRefPtr<DrawingBuffer> DrawingBuffer::create(blink::WebGraphicsContext3D* con
     return drawingBuffer.release();
 }
 
-DrawingBuffer::DrawingBuffer(blink::WebGraphicsContext3D* context,
+DrawingBuffer::DrawingBuffer(PassOwnPtr<blink::WebGraphicsContext3D> context,
     bool multisampleExtensionSupported,
     bool packedDepthStencilExtensionSupported,
     PreserveDrawingBuffer preserve,
@@ -136,7 +135,7 @@ DrawingBuffer::DrawingBuffer(blink::WebGraphicsContext3D* context,
 
 DrawingBuffer::~DrawingBuffer()
 {
-    releaseResources();
+    ASSERT(!m_context);
 }
 
 void DrawingBuffer::markContentsChanged()
@@ -158,7 +157,7 @@ void DrawingBuffer::markLayerComposited()
 
 blink::WebGraphicsContext3D* DrawingBuffer::context()
 {
-    return m_context;
+    return m_context.get();
 }
 
 bool DrawingBuffer::prepareMailbox(blink::WebExternalTextureMailbox* outMailbox, blink::WebExternalBitmap* bitmap)
@@ -184,7 +183,7 @@ bool DrawingBuffer::prepareMailbox(blink::WebExternalTextureMailbox* outMailbox,
 
     // We must restore the texture binding since creating new textures,
     // consuming and producing mailboxes changes it.
-    ScopedTextureUnit0BindingRestorer restorer(m_context, m_activeTextureUnit, m_texture2DBinding);
+    ScopedTextureUnit0BindingRestorer restorer(m_context.get(), m_activeTextureUnit, m_texture2DBinding);
 
     // First try to recycle an old buffer.
     RefPtr<MailboxInfo> frontColorBufferMailbox = recycledMailbox();
@@ -231,6 +230,11 @@ bool DrawingBuffer::prepareMailbox(blink::WebExternalTextureMailbox* outMailbox,
 
 void DrawingBuffer::mailboxReleased(const blink::WebExternalTextureMailbox& mailbox)
 {
+    if (m_selfToWaitForMailboxes) {
+        releaseSelf(mailbox);

[Justin Novosad, 2014/02/18 18:07:33]

naming nit: releaseSelfIfNeeded or releaseSelfIfFinalMailboxReleased

+        return;
+    }
+
     for (size_t i = 0; i < m_textureMailboxes.size(); i++) {
         RefPtr<MailboxInfo> mailboxInfo = m_textureMailboxes[i];
         if (!memcmp(mailboxInfo->mailbox.name, mailbox.name, sizeof(mailbox.name))) {
@@ -242,6 +246,27 @@ void DrawingBuffer::mailboxReleased(const blink::WebExternalTextureMailbox& mail
     ASSERT_NOT_REACHED();
 }
 
+
+void DrawingBuffer::releaseSelf(const blink::WebExternalTextureMailbox& mailbox)
+{
+    ASSERT(!m_textureMailboxes.isEmpty());
+    for (size_t i = 0; i < m_textureMailboxes.size(); i++) {
+        RefPtr<MailboxInfo> mailboxInfo = m_textureMailboxes[i];
+        if (!memcmp(mailboxInfo->mailbox.name, mailbox.name, sizeof(mailboxInfo->mailbox.name))) {
+            m_context->makeContextCurrent();
+            m_context->deleteTexture(mailboxInfo->textureId);
+            m_textureMailboxes.remove(i);
+            break;
+        }
+    }
+    if (!m_textureMailboxes.isEmpty())
+        return;
+
+    m_context.clear();
+    m_layer.clear();
+    m_selfToWaitForMailboxes.clear();
+}
+
 PassRefPtr<DrawingBuffer::MailboxInfo> DrawingBuffer::recycledMailbox()
 {
     if (m_recycledMailboxes.isEmpty())
@@ -416,8 +441,18 @@ void DrawingBuffer::releaseResources()
 
     clearPlatformLayer();
 
-    for (size_t i = 0; i < m_textureMailboxes.size(); i++)
-        m_context->deleteTexture(m_textureMailboxes[i]->textureId);
+    for (size_t i = 0; i < m_recycledMailboxes.size(); i++) {
+        m_context->deleteTexture(m_recycledMailboxes[i]->textureId);
+
+        for (size_t j = 0; j < m_textureMailboxes.size(); j++) {
+            RefPtr<MailboxInfo> mailboxInfo = m_textureMailboxes[j];
+            if (mailboxInfo->textureId == m_recycledMailboxes[i]->textureId) {
+                ASSERT(!memcmp(mailboxInfo->mailbox.name, m_recycledMailboxes[i]->mailbox.name, sizeof(mailboxInfo->mailbox.name)));
+                m_textureMailboxes.remove(j);
+                break;
+            }
+        }
+    }
 
     if (m_multisampleColorBuffer)
         m_context->deleteRenderbuffer(m_multisampleColorBuffer);
@@ -437,7 +472,7 @@ void DrawingBuffer::releaseResources()
     if (m_fbo)
         m_context->deleteFramebuffer(m_fbo);
 
-    m_context = 0;
+    setSize(IntSize());
 
     m_colorBuffer = 0;
     m_frontColorBuffer = 0;
@@ -450,12 +485,16 @@ void DrawingBuffer::releaseResources()
     m_contextEvictionManager.clear();
 
     m_recycledMailboxes.clear();
-    m_textureMailboxes.clear();
 
-    if (m_layer) {
+    if (m_layer)
         GraphicsLayer::unregisterContentsLayer(m_layer->layer());
+
+    if (m_textureMailboxes.isEmpty()) {
+        m_context.clear();
         m_layer.clear();
+        return;
     }
+    m_selfToWaitForMailboxes = this;
 }
 
 unsigned DrawingBuffer::createColorTexture(const IntSize& size)