Merge 198671 "Try fast-fetch rather than full fetch if drive::Fi..."

Merge 198671 "Try fast-fetch rather than full fetch if drive::Fi..."

> Try fast-fetch rather than full fetch if drive::FileSystem::GetEntryInfo failed.
> 
> GetEntryInfoByPath is not only used for querying an entry info,
> but also for just testing the existence of an entry.
> So, it is not always desirable to start full fetch when
> it does not exist locally.
> 
> The new implementation falls back to full fetch after all
> when the parent directory's entry is not ready either.
> This should not be an issue, however.
> Existence testing most typically happens when user tries to
> put a new file in a folder, in which case, the folder is
> already opened in UI and hence loaded.
> 
> BUG=236708
> TEST=the steps explained in BUG.
> R=satorux@chromium.org
> 
> Review URL: https://codereview.chromium.org/14838003
> 
> Patch from Kazuhiro Inaba <kinaba@chromium.org>;.

TBR=hashimoto@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=199689

[hashimoto, 2013-05-13 08:49:23]

Committed patchset #1 manually as r199689.