Lose/restore WebGL contexts if multisampling blackist status changes at runtime.

Source/core/platform/graphics/gpu/DrawingBuffer.cpp

Index: Source/core/platform/graphics/gpu/DrawingBuffer.cpp
diff --git a/Source/core/platform/graphics/gpu/DrawingBuffer.cpp b/Source/core/platform/graphics/gpu/DrawingBuffer.cpp
index a2c3725bfae6d0697911d1d6c6271e50a3d7bb56..9ba8e5b3c264eaba03c1b987d0ac92bc789be822 100644
--- a/Source/core/platform/graphics/gpu/DrawingBuffer.cpp
+++ b/Source/core/platform/graphics/gpu/DrawingBuffer.cpp
@@ -83,8 +83,7 @@ private:
 PassRefPtr<DrawingBuffer> DrawingBuffer::create(GraphicsContext3D* context, const IntSize& size, PreserveDrawingBuffer preserve, PassRefPtr<ContextEvictionManager> contextEvictionManager)
 {
     Extensions3D* extensions = context->getExtensions();
-    bool multisampleSupported = extensions->maySupportMultisampling()

[Ken Russell (switch to Gerrit), 2013/05/06 22:12:22]

Per my comment on the Chromium-side CL, I think this should probably be handled
differently, and no change to this code should be made.

[bajones, 2013/05/06 22:44:14]

I can put this line back for clarity, but it's not doing what you think it's
doing. Following the call chain down to WebGraphics3D it is hard coded to return
true.

The actual query of the multisampling blacklist entry is done in the
multisample() call via m_attributes.antialias

[Ken Russell (switch to Gerrit), 2013/05/07 00:33:22]

Let's please leave this line alone then. It sounds like a separate CL should
just delete Extensions3D::maySupportMultisampling().

-        && extensions->supports("GL_ANGLE_framebuffer_blit")
+    bool multisampleSupported = extensions->supports("GL_ANGLE_framebuffer_blit")
         && extensions->supports("GL_ANGLE_framebuffer_multisample")
         && extensions->supports("GL_OES_rgb8_rgba8");
     if (multisampleSupported) {