[Android] Remove public modifier for some internal classes.

There are some internal classes which should not be exposed for external usage.
This patch fixes some of them, including:
1. Merge XWalkResourceClientImpl.java and XWalkUIClientImpl.java into
XWalkResourceClient.java and XWalkUIClient.java.
2. Remove the public modifier for XWalkContent. All tests are based on
XWalkView.java.
3. Fix bugs for 'XWalkView.load()' if the data is set.

BUG=https://crosswalk-project.org/jira/browse/XWALK-1481
[Android] Use library Context to get Inflater for shared mode

For color picker on Android, it uses ColorPickerAdvanced and
ColorPickerSimple which is customized view. So the inflater
should contain the ClassLoader which has loaded the relevant
classes. As for shared mode, it's library Context.

BUG=https://crosswalk-project.org/jira/browse/XWALK-1534
Bump version to 6.35.125.0
Merge pull request #1844 from wang16/color_picker_crash

[Android] Use library Context to get Inflater for shared mode
Merge pull request #1841 from yongsheng/embeddingapi

[Android] Remove public modifier for some internal classes.