Fixing a crash due to calling [RWHVCocoa attributedSubstringForProposedRange] when there is no focu…

Fixing a crash due to calling [RWHVCocoa attributedSubstringForProposedRange] when there is no focused <input>.

RWHVCocoa::attributedSubstringForProposedRange maybe called when there is no
focused <input>. In such cases, renderWidgetHostView_->GetCompositionInfo() returns
nullptr.

BUG=698672
Review-Url: https://codereview.chromium.org/2732143002
Cr-Commit-Position: refs/heads/master@{#455028}
(cherry picked from commit 8c80b233da12ca81bece40f77b990a84a13c75a2)

Review-Url: https://codereview.chromium.org/2740743003 .
Cr-Commit-Position: refs/branch-heads/3029@{#65}
Cr-Branched-From: 939b32ee5ba05c396eef3fd992822fcca9a2e262-refs/heads/master@{#454471}
Committed: https://chromium.googlesource.com/chromium/src/+/e63f1c2fb0a59ee8d29ab49a946cb1c5c24e3d2d

[EhsanK, 2017-03-08 20:23:15]

Description was changed from

==========
Fixing a crash due to calling [RWHVCocoa attributedSubstringForProposedRange]
when there is no focused <input>.

RWHVCocoa::attributedSubstringForProposedRange maybe called when there is no
focused <input>. In such cases, renderWidgetHostView_->GetCompositionInfo()
returns
nullptr.

BUG=698672

Review-Url: https://codereview.chromium.org/2732143002
Cr-Commit-Position: refs/heads/master@{#455028}
(cherry picked from commit 8c80b233da12ca81bece40f77b990a84a13c75a2)
==========

to

==========
Fixing a crash due to calling [RWHVCocoa attributedSubstringForProposedRange]
when there is no focused <input>.

RWHVCocoa::attributedSubstringForProposedRange maybe called when there is no
focused <input>. In such cases, renderWidgetHostView_->GetCompositionInfo()
returns
nullptr.

BUG=698672

Review-Url: https://codereview.chromium.org/2732143002
Cr-Commit-Position: refs/heads/master@{#455028}
(cherry picked from commit 8c80b233da12ca81bece40f77b990a84a13c75a2)

Review-Url: https://codereview.chromium.org/2740743003 .
Cr-Commit-Position: refs/branch-heads/3029@{#65}
Cr-Branched-From:
939b32ee5ba05c396eef3fd992822fcca9a2e262-refs/heads/master@{#454471}
Committed:
https://chromium.googlesource.com/chromium/src/+/e63f1c2fb0a59ee8d29ab49a946c...
==========

[EhsanK, 2017-03-08 20:23:16]

Committed patchset #1 (id:1) manually as
e63f1c2fb0a59ee8d29ab49a946cb1c5c24e3d2d.