Make various string_util functions take StringPieces instead of char[].

chrome/browser/guest_view/web_view/web_view_guest.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/guest_view/web_view/web_view_guest.h"
 
 #include "base/debug/stack_trace.h"
 #include "base/message_loop/message_loop.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
@@ skipping 789 matching lines @@
 
 void WebViewGuest::DidFailProvisionalLoad(
     int64 frame_id,
     const base::string16& frame_unique_name,
     bool is_main_frame,
     const GURL& validated_url,
     int error_code,
     const base::string16& error_description,
     content::RenderViewHost* render_view_host) {
   // Translate the |error_code| into an error string.
-  std::string error_type;
-  base::RemoveChars(net::ErrorToString(error_code), "net::", &error_type);
+  std::string error_type(net::ErrorToString(error_code));
+  DCHECK(StartsWithASCII(error_type, "net::", true));

[darin (slow to review), 2014/05/22 23:49:46]

I don't know that it is guaranteed that the error description of blink-generated
errors will all start with "net::". I think this DCHECK is suspicious or at
least quite fragile.

[Peter Kasting, 2014/05/22 23:54:50]

net::ErrorToString() prefixes "net::" onto all return values.  If you're worried
that won't be true in the future, I could make some of these callsites
conditional.

[darin (slow to review), 2014/05/30 00:03:17]

Oh, nevermind. I was mistakenly thinking the string came from a WebURLError. You
can't be sure that a WebURLError's description string came from the network
stack. Sorry for the confusion on my part!

+  error_type.erase(0, 5);
   LoadAbort(is_main_frame, validated_url, error_type);
 }
 
 void WebViewGuest::DidStartProvisionalLoadForFrame(
     int64 frame_id,
     int64 parent_frame_id,
     bool is_main_frame,
     const GURL& validated_url,
     bool is_error_page,
     bool is_iframe_srcdoc,
@@ skipping 194 matching lines @@
 
   // Do not allow navigating a guest to schemes other than known safe schemes.
   // This will block the embedder trying to load unwanted schemes, e.g.
   // chrome://settings.
   bool scheme_is_blocked =
       (!content::ChildProcessSecurityPolicy::GetInstance()->IsWebSafeScheme(
           url.scheme()) &&
       !url.SchemeIs(content::kAboutScheme)) ||
       url.SchemeIs(content::kJavaScriptScheme);
   if (scheme_is_blocked || !url.is_valid()) {
-    std::string error_type;
-    base::RemoveChars(net::ErrorToString(net::ERR_ABORTED), "net::",
-                      &error_type);
+    std::string error_type(net::ErrorToString(net::ERR_ABORTED));
+    DCHECK(StartsWithASCII(error_type, "net::", true));
+    error_type.erase(0, 5);
     LoadAbort(true /* is_top_level */, url, error_type);
     return;
   }
 
   GURL validated_url(url);
   guest_web_contents()->GetRenderProcessHost()->
       FilterURL(false, &validated_url);
   // As guests do not swap processes on navigation, only navigations to
   // normal web URLs are supported.  No protocol handlers are installed for
   // other schemes (e.g., WebUI or extensions), and no permissions or bindings
@@ skipping 311 matching lines @@
     bool allow,
     const std::string& user_input) {
   WebViewGuest* guest =
       WebViewGuest::From(embedder_render_process_id(), new_window_instance_id);
   if (!guest)
     return;
 
   if (!allow)
     guest->Destroy();
 }