Commits on Nov 30, 2018

1. Fix cache synchronization crash with blob images. …

   On the first pass of prepare_transaction:
   1) Resource update contains only an AddBlobImage, but it is not visible according to viewport_tiles (set in SetBlobImageVisibleArea)
   2) We call ResourceCache::create_blob_scene_builder_requests but since the image is not visible, it doesn't create any BlobImageParams entries (containing the blob image key) to be stored in txn.blob_requests
   3) Since the transaction has no blob image updates, we can take the shortcut to call RenderBackend::update_document directly
   4) We didn't call ResourceCache::set_blob_rasterizer with the updated txn.blob_rasterizer.
   
   On the second pass of prepare_transaction:
   1) Resource update contains only an SetBlobImageVisibleArea
   2) We don't call ResourceCache::create_blob_scene_builder_requests since there is no Add/UpdateBlobImage entries.
   3) Since the transaction has no blob image updates, we can take the shortcut to call RenderBackend::update_document directly
   4) We are missing the blob we added in the previous step in ResourceCache::request_image, and it adds it to missing_blob_images.
   5) We try to process missing_blob_images in ResourceCache::rasterize_missing_blob_images with the old blob_rasterizer.
   6) Crash.
   
   Potentially fixes bug 1492241.

   

   aosmond committed Nov 30, 2018

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