Adds the ability to opt out of Safe Browsing download feedback from settings.

Notes:
- The download feedback pref is an enum with a ternary (not binary) value. As a result, need to set up a special handler to toggle the checkbox appropriately.
- Moved DownloadReportingStatus enum from DownloadFeedbackDialogView into DownloadFeedbackService. This lets BrowserOptionsHandler use the enum.

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How to test (currently Win & CrOS only):

A
1. Go to chrome://settings on a clean build; search for 'Privacy'
2. Verify that "Send suspicious downloaded files to Google" is not checked

B
1. Visit http://testsafebrowsing.appspot.com/, click on #5
2. Click discard in the download item
3. Click 'No thanks' in the dialog
4. Go to chrome://settings; search for 'Privacy'
5. Verify that "Send suspicious downloaded files to Google" is not checked

C
1. Clear your user preferences (e.g., delete the Preferences file in your user data directory)
2. Visit http://testsafebrowsing.appspot.com/, click on #5
3. Click discard in the download item
4. Click 'OK' in the dialog
5. Go to chrome://settings; search for 'Privacy'
6. Verify that "Send suspicious downloaded files to Google" is checked
-----------

BUG=312533

Review URL: https://codereview.chromium.org/153353006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251363 0039d316-1c4b-4281-b951-d872f2087c98
[Android] Don't wait for background tabs

The session restore tests were timing out on Android. This was because
they were waiting for the background tabs to be loaded, which they
would not be in normal startup.

The only reason the test worked at all is that when devtools accessed
the background tabs this forced them to be loaded.

This changes the test to only wait for, and to only measure, the
foreground tab.

NOTRY=true
BUG=343168,343900

Review URL: https://codereview.chromium.org/161473002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251364 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 251364
Explicitly provide path to C built-in includes in libc++ builds.

Temporary workaround for a goma bug.

BUG=337426
TBR=glider@chromium.org

Review URL: https://codereview.chromium.org/167113004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251365 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 251365