make multibuffer work with layout tests
This Cl does four things:
1) Makes sure that the loading state callback is handled in a backwards-compatible way.
(BufferedDataSource)
2) Fixes a problem where we would try to read past the end of the file if the file was
already completely cached. (MultiBufferReader)
3) Fixes one layout test that relies on a file getting read from the server slowly.
4) Avoids going back to the beginning of the block when server chooses to return less
data than we asked for. (ResourceMultiBufferDataProvider)
+ adds a few more DVLOG statements which I found very useful when debugging.
Review URL: https://codereview.chromium.org/1509663003
Cr-Commit-Position: refs/heads/master@{#365371}
8 files changed
