Share Group plumbing in Blink; Remove WebGL from default share group

Source/platform/graphics/gpu/DrawingBuffer.cpp

 /*
  * Copyright (c) 2010, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 311 matching lines @@
     if (m_contentsChanged) {
         if (m_multisampleMode != None) {
             commit();
             if (!m_framebufferBinding)
                 bind();
             else
                 restoreFramebufferBinding();
         }
         m_context->flush();
     }
-    Platform3DObject sourceTexture = m_colorBuffer;
+
+    if (!Extensions3DUtil::canUseCopyTextureCHROMIUM(internalFormat, destType, level))
+        return false;
+
+    GLint boundTexture = 0;
+    m_context->getIntegerv(GL_TEXTURE_BINDING_2D, &boundTexture);
+
+    // Contexts may be in a different share group. We must transfer the texture through a mailbox first
+    RefPtr<MailboxInfo> bufferMailbox = adoptRef(new MailboxInfo());
+    m_context->genMailboxCHROMIUM(bufferMailbox->mailbox.name);
+    m_context->bindTexture(GL_TEXTURE_2D, m_colorBuffer);
+    m_context->produceTextureCHROMIUM(GL_TEXTURE_2D, bufferMailbox->mailbox.name);
+    m_context->flush();
+
+    bufferMailbox->mailbox.syncPoint = m_context->insertSyncPoint();
+    m_context->waitSyncPoint(bufferMailbox->mailbox.syncPoint);

[piman, 2014/03/11 00:02:24]

This is essentially a noop. You insert a sync point in one context, and wait on
the same context. What you should do instead is move the wait onto |context|
before the consumeTextureCHROMIUM.

+
+    m_context->bindTexture(GL_TEXTURE_2D, boundTexture);
 
     if (!context->makeContextCurrent())
         return false;
 
-    if (!Extensions3DUtil::canUseCopyTextureCHROMIUM(internalFormat, destType, level))
-        return false;
+    Platform3DObject sourceTexture = context->createTexture();
+
+    context->getIntegerv(GL_TEXTURE_BINDING_2D, &boundTexture);
+    context->bindTexture(GL_TEXTURE_2D, sourceTexture);
+    context->consumeTextureCHROMIUM(GL_TEXTURE_2D, bufferMailbox->mailbox.name);
 
     bool unpackPremultiplyAlphaNeeded = false;
     bool unpackUnpremultiplyAlphaNeeded = false;
     if (m_attributes.alpha && m_attributes.premultipliedAlpha && !premultiplyAlpha)
         unpackUnpremultiplyAlphaNeeded = true;
     else if (m_attributes.alpha && !m_attributes.premultipliedAlpha && premultiplyAlpha)
         unpackPremultiplyAlphaNeeded = true;
 
     context->pixelStorei(GC3D_UNPACK_UNPREMULTIPLY_ALPHA_CHROMIUM, unpackUnpremultiplyAlphaNeeded);
     context->pixelStorei(GC3D_UNPACK_PREMULTIPLY_ALPHA_CHROMIUM, unpackPremultiplyAlphaNeeded);
     context->pixelStorei(GC3D_UNPACK_FLIP_Y_CHROMIUM, flipY);
     context->copyTextureCHROMIUM(GL_TEXTURE_2D, sourceTexture, texture, level, internalFormat, destType);
     context->pixelStorei(GC3D_UNPACK_FLIP_Y_CHROMIUM, false);
     context->pixelStorei(GC3D_UNPACK_UNPREMULTIPLY_ALPHA_CHROMIUM, false);
     context->pixelStorei(GC3D_UNPACK_PREMULTIPLY_ALPHA_CHROMIUM, false);
+
+    context->bindTexture(GL_TEXTURE_2D, boundTexture);
+    context->deleteTexture(sourceTexture);
+
     context->flush();

[piman, 2014/03/11 00:02:24]

If you wanted to be thorough, you would want to insert a sync point on
|context|, and wait on |m_context| here. This would ensure |m_context| can't
delete the texture before |context| had a chance to consume it.

(since everything is in the same channel currently, you won't see it as a race
today, but we might in the future).

 
     return true;
 }
 
 Platform3DObject DrawingBuffer::framebuffer() const
 {
     return m_fbo;
 }
 
 blink::WebLayer* DrawingBuffer::platformLayer()
@@ skipping 532 matching lines @@
     }
 }
 
 void DrawingBuffer::texImage2DResourceSafe(GLenum target, GLint level, GLenum internalformat, GLsizei width, GLsizei height, GLint border, GLenum format, GLenum type, GLint unpackAlignment)
 {
     ASSERT(unpackAlignment == 1 || unpackAlignment == 2 || unpackAlignment == 4 || unpackAlignment == 8);
     m_context->texImage2D(target, level, internalformat, width, height, border, format, type, 0);
 }
 
 } // namespace WebCore