Allow the creation of partially spoofed user agents

content/browser/android/content_view_core_impl.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/browser/android/content_view_core_impl.h"
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_array.h"
 #include "base/android/jni_string.h"
 #include "base/android/scoped_java_ref.h"
 #include "base/json/json_writer.h"
 #include "content/browser/android/content_view_client.h"
 #include "content/browser/android/load_url_params.h"
 #include "content/browser/android/touch_point.h"
 #include "content/browser/renderer_host/java/java_bound_object.h"
 #include "content/browser/renderer_host/java/java_bridge_dispatcher_host_manager.h"
 #include "content/browser/renderer_host/render_view_host_impl.h"
 #include "content/browser/renderer_host/render_widget_host_impl.h"
 #include "content/browser/renderer_host/render_widget_host_view_android.h"
 #include "content/browser/web_contents/navigation_controller_impl.h"
 #include "content/public/browser/browser_context.h"
 #include "content/public/browser/favicon_status.h"
 #include "content/public/browser/interstitial_page.h"
 #include "content/public/browser/navigation_entry.h"
 #include "content/public/browser/notification_details.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/notification_source.h"
 #include "content/public/browser/notification_types.h"
 #include "content/public/browser/web_contents.h"
+#include "content/public/common/content_client.h"
 #include "content/public/common/page_transition_types.h"
 #include "jni/ContentViewCore_jni.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebBindings.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebInputEvent.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/android/WebInputEventFactory.h"
 #include "ui/gfx/android/java_bitmap.h"
+#include "webkit/glue/user_agent.h"
 #include "webkit/glue/webmenuitem.h"
 
 using base::android::AttachCurrentThread;
 using base::android::ConvertJavaStringToUTF16;
 using base::android::ConvertJavaStringToUTF8;
 using base::android::ConvertUTF16ToJavaString;
 using base::android::ConvertUTF8ToJavaString;
 using base::android::GetClass;
 using base::android::HasField;
 using base::android::JavaByteArrayToByteVector;
@@ skipping 42 matching lines @@
       web_contents_(static_cast<WebContentsImpl*>(web_contents)),
       tab_crashed_(false) {
   DCHECK(web_contents) <<
       "A ContentViewCoreImpl should be created with a valid WebContents.";
 
   InitJNI(env, obj);
 
   notification_registrar_.Add(this,
                               NOTIFICATION_EXECUTE_JAVASCRIPT_RESULT,
                               NotificationService::AllSources());
+
+  // Currently, the only use case we have for overriding a user agent involves
+  // spoofing a desktop Linux user agent for "Request desktop site".
+  // Automatically set it for all WebContents.

[Charlie Reis, 2012/08/24 21:38:43]

I don't understand this comment.  Request desktop site isn't on by default, is
it?  Why would this be set for all WebContents?

[gone, 2012/08/24 23:50:35]

The main reason we set it here is that we don't save the user agent override out
in our version of the tab restoration pipeline.  The reasoning for doing so was
to ensure that our override string could report proper Chromium version numbers
while spoofing the rest of the string.  Since there isn't any way to set the
string manually, a user could potentially get stuck with an out-of-date string
until they opened a new tab and surfed with that.  It also saves some storage
space since we always override with the same string, but that's a minor thing.

As a consequence, the override has to be re-set for the WebContents when the
browser restarts; the constructor catches both this case and the case where the
user toggles the overrides on for a tab for the first time.  The alternative is
to set it in both of those locations; I don't have a strong opinion either way
and could switch over, if necessary.

[Charlie Reis, 2012/08/25 00:11:10]

Sorry if I'm just missing something basic, but is this just saying what the
overridden user agent should be if the user decides to use Request Desktop Site?
 (Rather than turning on the override by default?)  If so, please clarify that
in the comment, since I didn't get it.

[gone, 2012/08/25 00:23:49]

D'oh, yeah, that's all that does.  It just sets the string for when it's needed
and doesn't turn it on by default.  I'll clarify in the comment.

+  const char kLinuxInfoStr[] = "X11; Linux x86_64";
+  std::string product = content::GetContentClient()->GetProduct();
+  std::string spoofed_ua =
+      webkit_glue::BuildUserAgentFromOSAndProduct(kLinuxInfoStr, product);
+  web_contents->SetUserAgentOverride(spoofed_ua);
 }
 
 ContentViewCoreImpl::~ContentViewCoreImpl() {
   // Make sure nobody calls back into this object while we are tearing things
   // down.
   notification_registrar_.RemoveAll();
 
   delete java_object_;
   java_object_ = NULL;
   java_ref_.reset();
@@ skipping 508 matching lines @@
   if (!HasField(env, clazz, "mNativeContentViewCore", "I")) {
     DLOG(ERROR) << "Unable to find ContentView.mNativeContentViewCore!";
     return false;
   }
   g_native_content_view = GetFieldID(env, clazz, "mNativeContentViewCore", "I");
 
   return RegisterNativesImpl(env) >= 0;
 }
 
 }  // namespace content