Save/restore PBO bindings in DrawingBuffer

third_party/WebKit/Source/platform/graphics/gpu/DrawingBuffer.h

Index: third_party/WebKit/Source/platform/graphics/gpu/DrawingBuffer.h
diff --git a/third_party/WebKit/Source/platform/graphics/gpu/DrawingBuffer.h b/third_party/WebKit/Source/platform/graphics/gpu/DrawingBuffer.h
index 737fad85b105be200e68026ac5d0a39a8cd20f5e..3fc461050db472486a51ffd4b757adf7300533a1 100644
--- a/third_party/WebKit/Source/platform/graphics/gpu/DrawingBuffer.h
+++ b/third_party/WebKit/Source/platform/graphics/gpu/DrawingBuffer.h
@@ -136,6 +136,19 @@ public:
     // The bound texture is tracked to avoid costly queries during rendering.
     void setTexture2DBinding(GLuint texture) { m_texture2DBinding = texture; }
 
+    void setPixelUnpackBufferBinding(GLuint buffer)
+    {
+        DCHECK(m_webGLVersion > WebGL1);
+        m_pixelUnpackBufferBinding = buffer;
+    }
+
+    void notifyBufferDeleted(GLuint buffer)
+    {
+        if (m_webGLVersion > WebGL1 && buffer == m_pixelUnpackBufferBinding) {
+            setPixelUnpackBufferBinding(0);
+        }
+    }
+
     // The DrawingBuffer needs to track the currently bound framebuffer so it
     // restore the binding when needed.
     void setFramebufferBinding(GLenum target, GLuint fbo)
@@ -227,6 +240,8 @@ public:
     int sampleCount() const { return m_sampleCount; }
     bool explicitResolveOfMultisampleData() const { return m_antiAliasingMode == MSAAExplicitResolve; }
 
+    void restorePixelUnpackBufferBindings();
+
     // Bind to m_drawFramebufferBinding or m_readFramebufferBinding if it's not 0.
     // Otherwise, bind to the default FBO.
     void restoreFramebufferBindings();
@@ -377,6 +392,7 @@ private:
     const WebGLVersion m_webGLVersion;
     bool m_scissorEnabled = false;
     GLuint m_texture2DBinding = 0;
+    GLuint m_pixelUnpackBufferBinding = 0;
     GLuint m_drawFramebufferBinding = 0;
     GLuint m_readFramebufferBinding = 0;
     GLuint m_renderbufferBinding = 0;