Support clipboardData.getData() for Android

Support clipboardData.getData() for Android

APIs like clipboardData.getData("text/plain") was returning empty string.
DataObject was relying on ReadAvailableTypes() API to get the available types
before getting the actual data from the clipboard.
Since it was not implemented for android, clipboard content was never added
to DataObject or the DataTransfer object resulting in failure.

BUG=369101

[ams, 2015-03-27 15:16:23]

amit.srkr@samsung.com changed reviewers:
+ dcheng@chromium.org

[ams, 2015-03-27 15:17:21]

On 2015/03/27 15:16:23, ams wrote:
> mailto:amit.srkr@samsung.com changed reviewers:
> + mailto:dcheng@chromium.org

PTAL

[dcheng, 2015-03-27 15:38:56]

Is this covered by any tests?

[ams, 2015-03-31 10:23:44]

On 2015/03/27 15:38:56, dcheng wrote:
> Is this covered by any tests?

Hi,

Sorry for delayed response :-(
There are multiple tests in layouttests/editing/pasteboard, which covers this
aspect functionally.
LayoutTests/editing/pasteboard/onpaste-text-html.html
LayoutTests/editing/pasteboard/onpaste-text-html-types.html
LayoutTests/editing/pasteboard/paste-as-plaintext-only-has-text.html

When I ran these layout tests individually on android, strangely these are
passing. However if we run any of them manually (manual copy/paste instead of
execCommand), they fail similar to http://jsfiddle.net/_craigmr/5n9kv as
mentioned in the Bug.

Wondering how these tests are passing! 
The failure is also pretty evident from below code:
https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit...

[ams, 2015-04-13 07:09:48]

On 2015/03/31 10:23:44, ams wrote:
> On 2015/03/27 15:38:56, dcheng wrote:
> > Is this covered by any tests?
> 
> Hi,
> 
> Sorry for delayed response :-(
> There are multiple tests in layouttests/editing/pasteboard, which covers this
> aspect functionally.
> LayoutTests/editing/pasteboard/onpaste-text-html.html
> LayoutTests/editing/pasteboard/onpaste-text-html-types.html
> LayoutTests/editing/pasteboard/paste-as-plaintext-only-has-text.html
> 
> When I ran these layout tests individually on android, strangely these are
> passing. However if we run any of them manually (manual copy/paste instead of
> execCommand), they fail similar to http://jsfiddle.net/_craigmr/5n9kv as
> mentioned in the Bug.
> 
> Wondering how these tests are passing! 
> The failure is also pretty evident from below code:
>
https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit...

I found the reason for above.
The Layout-tests are only using mock_webclipboard_impl, thereby passing all the
tests.
So none of the layout-tests will be actually able to test actual clipboard in
android.

I would like to add some unittest for readAvailableTypes() though.
But I am unable to execute the clipboard test cases for android. 
I found that clipboard_android_test.cc is included under interactive_ui_tests,
which does not run for android.

@dcheng, 
could you please provide some pointer on this regard!