Move --user-agent overriding logic from chrome into content.

content/app/content_main_runner.cc

 // Copyright (c) 2012 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 "content/public/app/content_main_runner.h"
 
 #include "base/at_exit.h"
 #include "base/command_line.h"
 #include "base/debug/debugger.h"
 #include "base/debug/trace_event.h"
@@ skipping 205 matching lines @@
 
   if (delegate) delegate->ZygoteForked();
 
   // Zygote::HandleForkRequest may have reallocated the command
   // line so update it here with the new version.
   const CommandLine& command_line = *CommandLine::ForCurrentProcess();
 
   // If a custom user agent was passed on the command line, we need
   // to (re)set it now, rather than using the default one the zygote
   // initialized.
-  bool custom = false;
-  std::string ua = content::GetContentClient()->GetUserAgent(&custom);
-  if (custom) webkit_glue::SetUserAgent(ua, custom);
+  if (command_line.HasSwitch(switches::kUserAgent)) {
+    webkit_glue::SetUserAgent(
+        command_line.GetSwitchValueASCII(switches::kUserAgent), true);
+  }
 
   // The StatsTable must be initialized in each process; we already
   // initialized for the browser process, now we need to initialize
   // within the new processes as well.
   pid_t browser_pid = base::GetParentProcessId(
       base::GetParentProcessId(base::GetCurrentProcId()));
   InitializeStatsTable(browser_pid, command_line);
 
   content::MainFunctionParams main_params(command_line);
 
@@ skipping 221 matching lines @@
       // On linux, we're in the zygote here; so we need the parent process' id.
       browser_pid = base::GetParentProcessId(base::GetCurrentProcId());
 #endif
     }
 
     InitializeStatsTable(browser_pid, command_line);
 
     if (delegate)
       delegate->PreSandboxStartup();
 
+    // Set any custom user agent passed on the command line now so the string
+    // doesn't change between calls to webkit_glue::GetUserAgent(), otherwise it
+    // defaults to the user agent set during SetContentClient().
+    DCHECK(content::GetContentClient())
+        << "SetContentClient() must be called by this point in time";

[jam, 2012/04/06 23:13:52]

nit: are you sure this dcheck is necessary? ie. have you tried not setting it
and seen that you can get this far without a crash somewhere?

[scherkus (not reviewing), 2012/04/06 23:59:41]

if the call to SetContentClient() happens after setting a custom UA the it would
get clobbered due to SetContentClient() setting the default UA string

so really the DCHECK() is for protecting --user-agent but I suppose it could get
moved later down

I'll give it a shot

[jam, 2012/04/07 00:03:07]

just to be clear, i meant if there's code in content that's called earlier than
this point which does "content::GetContentClient()->". so it'd crash which is as
good a signal as this dcheck

+    if (command_line.HasSwitch(switches::kUserAgent)) {
+      webkit_glue::SetUserAgent(
+          command_line.GetSwitchValueASCII(switches::kUserAgent), true);
+    }
+
     if (!process_type.empty())
       CommonSubprocessInit(process_type);
 
 #if defined(OS_WIN)
     CHECK(content::InitializeSandbox(sandbox_info));
 #elif defined(OS_MACOSX)
     if (process_type == switches::kRendererProcess ||
         process_type == switches::kPpapiPluginProcess ||
         (delegate && delegate->DelaySandboxInitialization(process_type))) {
       // On OS X the renderer sandbox needs to be initialized later in the
@@ skipping 87 matching lines @@
 }  // namespace
 
 namespace content {
 
 // static
 ContentMainRunner* ContentMainRunner::Create() {
   return new ContentMainRunnerImpl();
 }
 
 }  // namespace content