Revert of Replace string::find(prefix) == 0 pattern with base::StartsWith().

Revert of Replace string::find(prefix) == 0 pattern with base::StartsWith(). (patchset #2 id:20001 of https://codereview.chromium.org/2121513002/ )

Reason for revert:
Bisect believes that this CL caused the Win builder to break. 

https://build.chromium.org/p/chromium/builders/Win%20x64/builds/2267
https://build.chromium.org/p/chromium/builders/Win/builds/45048

For context see:
https://bugs.chromium.org/p/chromium/issues/detail?id=626539

Original issue's description:
> Replace string::find(prefix) == 0 pattern with base::StartsWith().
> 
> base::StartsWith() should be O(|prefix|) whereas string::find() is
>   pretty bad, O(|string| * |prefix|).
> 
> TBR=jam@chromium.org
> BUG=None
> Test=None, internal cleanup.
> CQ_INCLUDE_TRYBOTS=tryserver.chromium.win:win10_chromium_x64_rel_ng
> 
> Committed: https://crrev.com/53bfbe932191085b5d69f824a9923bccc26d58dc
> Cr-Commit-Position: refs/heads/master@{#404307}

TBR=thestig@chromium.org,lazyboy@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=None

[markusheintz_, 2016-07-08 13:02:00]

The CQ bit was checked by markusheintz@chromium.org

[markusheintz_, 2016-07-08 13:02:00]

Created Revert of Replace string::find(prefix) == 0 pattern with
base::StartsWith().

[commit-bot: I haz the power, 2016-07-08 13:03:34]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-07-08 13:05:28]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-07-08 13:05:31]

Failed to apply patch for
chrome/browser/apps/guest_view/web_view_browsertest.cc:
While running git apply --index -3 -p1;
  error: patch failed:
chrome/browser/apps/guest_view/web_view_browsertest.cc:2355
  error: repository lacks the necessary blob to fall back on 3-way merge.
  error: chrome/browser/apps/guest_view/web_view_browsertest.cc: patch does not
apply

Patch:       chrome/browser/apps/guest_view/web_view_browsertest.cc
Index: chrome/browser/apps/guest_view/web_view_browsertest.cc
diff --git a/chrome/browser/apps/guest_view/web_view_browsertest.cc
b/chrome/browser/apps/guest_view/web_view_browsertest.cc
index
f8f2f81348ef7136003d8377ac509ec84c8dcb67..5cd24d4cde654f215d2607f88e736b488591f8a7
100644
--- a/chrome/browser/apps/guest_view/web_view_browsertest.cc
+++ b/chrome/browser/apps/guest_view/web_view_browsertest.cc
@@ -2355,8 +2355,7 @@
 std::unique_ptr<net::test_server::HttpResponse>
HandleDownloadRequestWithCookie(
     std::queue<net::HttpStatusCode>* status_codes,
     const net::test_server::HttpRequest& request) {
-  if (!base::StartsWith(request.relative_url, kDownloadPathPrefix,
-                        base::CompareCase::SENSITIVE)) {
+  if (request.relative_url.find(kDownloadPathPrefix) != 0) {
     return std::unique_ptr<net::test_server::HttpResponse>();
   }

[Lei Zhang, 2016-07-13 16:14:18]

Description was changed from

==========
Revert of Replace string::find(prefix) == 0 pattern with base::StartsWith().
(patchset #2 id:20001 of https://codereview.chromium.org/2121513002/ )

Reason for revert:
Bisect believes that this CL caused the Win builder to break. 

https://build.chromium.org/p/chromium/builders/Win%20x64/builds/2267
https://build.chromium.org/p/chromium/builders/Win/builds/45048

For context see:
https://bugs.chromium.org/p/chromium/issues/detail?id=626539

Original issue's description:
> Replace string::find(prefix) == 0 pattern with base::StartsWith().
> 
> base::StartsWith() should be O(|prefix|) whereas string::find() is
>   pretty bad, O(|string| * |prefix|).
> 
> TBR=jam@chromium.org
> BUG=None
> Test=None, internal cleanup.
> CQ_INCLUDE_TRYBOTS=tryserver.chromium.win:win10_chromium_x64_rel_ng
> 
> Committed: https://crrev.com/53bfbe932191085b5d69f824a9923bccc26d58dc
> Cr-Commit-Position: refs/heads/master@{#404307}

TBR=thestig@chromium.org,lazyboy@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=None
==========

to

==========
Revert of Replace string::find(prefix) == 0 pattern with base::StartsWith().
(patchset #2 id:20001 of https://codereview.chromium.org/2121513002/ )

Reason for revert:
Bisect believes that this CL caused the Win builder to break. 

https://build.chromium.org/p/chromium/builders/Win%20x64/builds/2267
https://build.chromium.org/p/chromium/builders/Win/builds/45048

For context see:
https://bugs.chromium.org/p/chromium/issues/detail?id=626539

Original issue's description:
> Replace string::find(prefix) == 0 pattern with base::StartsWith().
> 
> base::StartsWith() should be O(|prefix|) whereas string::find() is
>   pretty bad, O(|string| * |prefix|).
> 
> TBR=jam@chromium.org
> BUG=None
> Test=None, internal cleanup.
> CQ_INCLUDE_TRYBOTS=tryserver.chromium.win:win10_chromium_x64_rel_ng
> 
> Committed: https://crrev.com/53bfbe932191085b5d69f824a9923bccc26d58dc
> Cr-Commit-Position: refs/heads/master@{#404307}

TBR=thestig@chromium.org,lazyboy@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=None
==========