Mark getter methods in ui::InputMethod as const

This CL marks following methods as "const-method"
as a preparation to fix issue 164964.
- ui::TextInputClient::GetCaretBounds
- ui::TextInputClient::GetCompositionCharacterBounds
- ui::TextInputClient::HasCompositionText
- ui::TextInputClient::GetTextRange
- ui::TextInputClient::GetCompositionTextRang
- ui::TextInputClient::GetSelectionRange
- ui::TextInputClient::GetTextFromRange

BUG=164964
TEST=none

Review URL: https://codereview.chromium.org/27812003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@230001 0039d316-1c4b-4281-b951-d872f2087c98
16 files changed