Add a cap of six in-flight requests per host to the ResourceScheduler

There's a cap of 10 delayable in-flight requests already present in the ResourceScheduler, but due to the underlying cap on six connections per host we sometimes don't utilize all ten if they're all for the same host. This CL adds an additional per-host cap, meaning if there's already six in-flight requests going to foo.bar.com, another request to foo.bar.com will be skipped in favour of a later-queued request to foo2.bar.com.

Tests from pmeenan@ suggests this results in an overall increase of onload and Speed Index speed by about 2.5%, and DOM Content Loaded speed by 1.15%. 

BUG=319488

Review URL: https://codereview.chromium.org/23620058

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235491 0039d316-1c4b-4281-b951-d872f2087c98
[sql] Recover Favicons v5 databases, with more recovery automation.

An entirely automated recovery system runs afoul of questions about
whether the corrupt database's schema can be trusted.
sql::Recovery::AutoRecoverTable() uses a schema created by the caller
to construct the recovery virtual table and then copies the data over.

sql::Recovery::SetupMeta() and GetMetaVersionNumber() simplify
accessing meta-table info in the corrupt database.

sql::test::IntegrityCheck() and CorruptSizeInHeader() helpers to
simplify common testing operations.

Rewrite ThumbnailDatabase v6 and v7 recovery code and tests using
these changes, and add a v5 recovery path.  Additionally handle
deprecated versions.

BUG=240396,109482

Review URL: https://codereview.chromium.org/50493012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235492 0039d316-1c4b-4281-b951-d872f2087c98
Cast: Store more than one last sent RTCP report for improved RTT.

Added a map that store the RTCP reports we sent and when they where sent
when we get an answer we can find it in our map; hence even if previus
RTCP packets have been lost we can calculate the RTT.

Review URL: https://codereview.chromium.org/60733020

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235493 0039d316-1c4b-4281-b951-d872f2087c98
Create and configure CastSender from chrome extensions API

Implement default codec parameters and translate CastRtpCaps to
AudioSenderConfig and VideoSenderConfig. This allows CastSender to be
be created with default parameters.

Adding an extensions test that exercise these code.

BUG=301920

Review URL: https://codereview.chromium.org/60733021

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235494 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 235494