[Android WebView] Prepare loading error messages for TC

[Android WebView] Prepare loading error messages for TC

While trying to hook up new strings from crrev.com/1270793002 into TC,
I have realized that some changes need to be made to their definitions.

1. In Chrome, html fragments (grit 'structures') are not used. Instead, they
   just put into .grd files as regular messages, with markup being isolated
   inside fake placeholders to avoid the translators messing with it.
   (and grit also requires non-empty 'example' tags to present for them).
   Thus, removed 'structure.html' and put its contents into a scary-looking
   message.

2. .grd files containing messages must not include anything, as only .grd
   files themselves are copied into the internal tree for processing.
   Thus, split the messages into a separate .grd file with no includes.

3. From the strings .grd, per-locale .pak files must be produced, and then
   all those xxx_strings_xx.pak files repacked into a single xx.pak file.
   As WebView already uses content_strings, changed the script to pack
   content_strings together with the new strings, and renamed the script
   accordingly.

4. As I would not like to repeat this process again would we need some
   native strings on the browser part, and as we share native resources
   between the browser and the renderer, moved the .grd files out from
   'renderer' into a new 'ui' subdir.

BUG=515691
Committed: https://crrev.com/56917048940d4ecd4854416cee2901965320dc89
Cr-Commit-Position: refs/heads/master@{#342367}

[mnaganov (inactive), 2015-08-06 20:34:52]

mnaganov@chromium.org changed reviewers:
+ torne@chromium.org

[Torne, 2015-08-07 13:51:51]

lgtm

[mnaganov (inactive), 2015-08-07 15:27:53]

The CQ bit was checked by mnaganov@chromium.org

[commit-bot: I haz the power, 2015-08-07 15:28:10]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1273263002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1273263002/1

[commit-bot: I haz the power, 2015-08-07 16:48:44]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-08-07 16:49:21]

Patchset 1 (id:??) landed as
https://crrev.com/56917048940d4ecd4854416cee2901965320dc89
Cr-Commit-Position: refs/heads/master@{#342367}