Replace usages of MessageLoopProxy with SequencedTaskRunner in the disk cache

This replaces most places where a MessageLoopProxy is passed around in
the disk cache to instead pass a SequencedTaskRunner. As a knock-on
effect, users of the disk cache have also been updated.

BUG=391045

Review URL: https://codereview.chromium.org/406753002

git-svn-id: http://src.chromium.org/svn/trunk/src/net@290990 4ff67af0-8c30-449e-8e8b-ad334ec8d88c
Set response headers for data URL.

Resources represented by a data URL will stay being considered to be
unique origin resource but are changed to allow cross origin access by
the Access-Control-Allow-Origin header.

We take this approach mainly because we want scripts in an iframe with
a data URL specified to its src attribute to be executed as a script on
a unique origin resource, not on the parent frame.

We can choose to treat "loading" of data URL specially as same origin
while execution as different origin. But such an approach complicates
security policy checking algorithm.

Grammar checking code is added to ensure we emit a valid content-type.

Blink side CL https://codereview.chromium.org/54173002/ will be landed
first to temporarily disable layout tests that will break, and then
this CL will be landed.

BUG=308768

Review URL: https://codereview.chromium.org/294193002

git-svn-id: http://src.chromium.org/svn/trunk/src/net@291007 4ff67af0-8c30-449e-8e8b-ad334ec8d88c
Add new histograms for tracking the reasons that QUIC sessions discard packets.

Review URL: https://codereview.chromium.org/493863002

git-svn-id: http://src.chromium.org/svn/trunk/src/net@291012 4ff67af0-8c30-449e-8e8b-ad334ec8d88c
Revert 291007 "Set response headers for data URL."

> Set response headers for data URL.
> 
> Resources represented by a data URL will stay being considered to be
> unique origin resource but are changed to allow cross origin access by
> the Access-Control-Allow-Origin header.
> 
> We take this approach mainly because we want scripts in an iframe with
> a data URL specified to its src attribute to be executed as a script on
> a unique origin resource, not on the parent frame.
> 
> We can choose to treat "loading" of data URL specially as same origin
> while execution as different origin. But such an approach complicates
> security policy checking algorithm.
> 
> Grammar checking code is added to ensure we emit a valid content-type.
> 
> Blink side CL https://codereview.chromium.org/54173002/ will be landed
> first to temporarily disable layout tests that will break, and then
> this CL will be landed.
> 
> BUG=308768
> 
> Review URL: https://codereview.chromium.org/294193002

TBR=tyoshino@chromium.org

Review URL: https://codereview.chromium.org/497443002

git-svn-id: http://src.chromium.org/svn/trunk/src/net@291015 4ff67af0-8c30-449e-8e8b-ad334ec8d88c
Remove unused UploadElement class.

It used to be used to pass upload information between Blink and
the browser process, but has not been used for some time.

BUG=none

Review URL: https://codereview.chromium.org/495703002

git-svn-id: http://src.chromium.org/svn/trunk/src/net@291019 4ff67af0-8c30-449e-8e8b-ad334ec8d88c
parameterize http response header tests

Followup to https://codereview.chromium.org/391763002 to allow this
to build on more compilers (which can fail when using structs defined
in funtions in arraysize calls- as mentioned in base/macros.h).

By refactoring to use TEST_P we can skip the manual loop entirely.

BUG=348877
TEST=net_unittests --gtest_filter=Http*

Review URL: https://codereview.chromium.org/448373003

git-svn-id: http://src.chromium.org/svn/trunk/src/net@291025 4ff67af0-8c30-449e-8e8b-ad334ec8d88c