Remove a couple NOTREACHED in ShellExtensionsBrowserClient

It turns out we do reach them occasionally when running real apps.

BUG=none
TEST=none
R=derat@chromium.org

Review URL: https://codereview.chromium.org/159063003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@250433 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 250433
<webview>: Enable WebViewInteractiveTest.DragDropWithinWebview test.

After removing synthetic mouseup on drag end (http://crrev.com/137663010/),
the test seems to not fail on try bots.
Sample 200 X 2 runs:
http://build.chromium.org/p/tryserver.chromium/builders/linux_chromeos/builds/200399/steps/interactive_ui_tests/logs/stdio
http://build.chromium.org/p/tryserver.chromium/builders/linux_chromeos/builds/200405/steps/interactive_ui_tests/logs/stdio
Let's enable it.

BUG=309032
Test=No functional change, enabling disabled test.

Review URL: https://codereview.chromium.org/159643002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@250434 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 250434
gesture nav: Fix the UX for some navigation edge cases.

The renderer does not always send the 'first visual non-empty paint' message
to the browser for navigations (e.g. when doing in-page navigation). As a
result, the screenshot overlay never hides in such cases. So force a repaint of
the page right after the page has completely loaded if the 'first paint' message
hasn't been received by then, and hide the overlay when the paint happens.

This also adds some test coverage for the overlay (including for this change).

BUG=342311
R=sky@chromium.org
TBR=piman@ for content_tets.gypi

Review URL: https://codereview.chromium.org/138253008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@250435 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 250435