Remove selected text when committing empty text

Remove selected text when committing empty text

Android's InputConnection API does not mention this, but replacing the
selected text by the new text seems to be the right behavior and is
consistent with EditText behavior. Also, this is consistent with
SetComposition()'s behavior for empty string.

In doing so,
- fix Editor to handle empty text and emit beforeinput event as expected
  (https://w3c.github.io/uievents/#beforeinput mentions empty string
  case)
- remove unnecessary code in WebLocalFrameImpl to fix test failures.

BUG=710621
Review-Url: https://codereview.chromium.org/2874783004
Cr-Original-Commit-Position: refs/heads/master@{#471228}
Review-Url: https://codereview.chromium.org/2883073002 .
Cr-Commit-Position: refs/branch-heads/3071@{#555}
Cr-Branched-From: a106f0abbf69dad349d4aaf4bcc4f5d376dd2377-refs/heads/master@{#464641}
Committed: https://chromium.googlesource.com/chromium/src/+/d48ab8de17a217029d45a9c7f9d73466cb747fad

[Changwan Ryu, 2017-05-15 17:10:53]

Description was changed from

==========
Remove selected text when committing empty text

Android's InputConnection API does not mention this, but replacing the
selected text by the new text seems to be the right behavior and is
consistent with EditText behavior. Also, this is consistent with
SetComposition()'s behavior for empty string.

In doing so,
- fix Editor to handle empty text and emit beforeinput event as expected
  (https://w3c.github.io/uievents/#beforeinput mentions empty string
  case)
- remove unnecessary code in WebLocalFrameImpl to fix test failures.

BUG=710621

Review-Url: https://codereview.chromium.org/2874783004
Cr-Commit-Position: refs/heads/master@{#471228}
(cherry picked from commit 79067c775b1196aa0be445effa8109d85ca82b68)
==========

to

==========
Remove selected text when committing empty text

Android's InputConnection API does not mention this, but replacing the
selected text by the new text seems to be the right behavior and is
consistent with EditText behavior. Also, this is consistent with
SetComposition()'s behavior for empty string.

In doing so,
- fix Editor to handle empty text and emit beforeinput event as expected
  (https://w3c.github.io/uievents/#beforeinput mentions empty string
  case)
- remove unnecessary code in WebLocalFrameImpl to fix test failures.

BUG=710621

Review-Url: https://codereview.chromium.org/2874783004
Cr-Original-Commit-Position: refs/heads/master@{#471228}
Review-Url: https://codereview.chromium.org/2883073002 .
Cr-Commit-Position: refs/branch-heads/3071@{#555}
Cr-Branched-From:
a106f0abbf69dad349d4aaf4bcc4f5d376dd2377-refs/heads/master@{#464641}
Committed:
https://chromium.googlesource.com/chromium/src/+/d48ab8de17a217029d45a9c7f9d7...
==========

[Changwan Ryu, 2017-05-15 17:10:55]

Committed patchset #1 (id:1) manually as
d48ab8de17a217029d45a9c7f9d73466cb747fad.