Makes a handful of DataSources not replace the existing

Makes a handful of DataSources not replace the existing
DataSource. In the long term all DataSources should do this, but for
now I've added a method that does it.

I recently added the IsRegistered method thinking registration should
look like:

  if (!contents->profile()->GetChromeURLDataManager()->IsRegistered(
      SomeSource::kSomeName)) {
    contents->profile()->GetChromeURLDataManager()->AddDataSource(
      new SomeSource());
  }

But this is too tedious. And long term we should make all sources
replace the existing one.

BUG=52022
TEST=none

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=75752

[Evan Martin, 2011-02-23 00:17:32]

LGTM

http://codereview.chromium.org/6546078/diff/1/chrome/browser/sessions/session...
File chrome/browser/sessions/session_restore_uitest.cc (right):

http://codereview.chromium.org/6546078/diff/1/chrome/browser/sessions/session...
chrome/browser/sessions/session_restore_uitest.cc:453:
TEST_F(SessionRestoreUITest, ShareProcessesOnRestore) {
Did you mean to include this?

[sky, 2011-02-23 00:38:57]

http://codereview.chromium.org/6546078/diff/1/chrome/browser/sessions/session...
File chrome/browser/sessions/session_restore_uitest.cc (right):

http://codereview.chromium.org/6546078/diff/1/chrome/browser/sessions/session...
chrome/browser/sessions/session_restore_uitest.cc:453:
TEST_F(SessionRestoreUITest, ShareProcessesOnRestore) {
On 2011/02/23 00:17:32, Evan Martin wrote:
> Did you mean to include this?

Yes. All the changes I've done to ChromeURLDataManager (and URLRequest,
ProcessIterator, process launcher and automation classes) are so this test isn't
flakey! Yowza!