Provide mutable members of UrlRequestContext via pure-virtual interface

net/url_request/url_request_context.h

Index: net/url_request/url_request_context.h
diff --git a/net/url_request/url_request_context.h b/net/url_request/url_request_context.h
index cea9de5b1a657d2631d5a8e7f99a957500ef3a1d..3a7d69802536951eb6ad6185c5c63f34e19b3bbb 100644
--- a/net/url_request/url_request_context.h
+++ b/net/url_request/url_request_context.h
@@ -40,6 +40,71 @@ class URLRequest;
 class URLRequestJobFactory;
 class URLRequestThrottlerManager;
 
+// A pure-virtual interface that provides the HTTP Accept-Language,
+// Accept-Charset and User-Agent header values.  An instance of an
+// implementation of this interface can be used by calling
+// |URLRequestContext::set_http_user_agent_settings()|.
+class NET_EXPORT HttpUserAgentSettings {

[erikwright (departed), 2012/09/21 15:06:33]

Move to http_user_agent_settings.h

+ public:
+  // Gets the value of 'Accept-Language' header field.
+  virtual const std::string& GetAcceptLanguage() = 0;
+  // Gets the value of 'Accept-Charset' header field.
+  virtual const std::string& GetAcceptCharset() = 0;
+  // Gets the UA string to use for the given URL.  Pass an invalid URL (such as

[erikwright (departed), 2012/09/21 15:06:33]

"Pass an invalid URL (such as GURL())" -> Pass an empty URL...

+  // GURL()) to get the default UA string.
+  virtual const std::string& GetUserAgent(const GURL& url) = 0;
+
+  virtual ~HttpUserAgentSettings() {}
+
+ protected:
+  HttpUserAgentSettings() {}

[erikwright (departed), 2012/09/21 15:06:33]

This can be public (no-one can call it because of the pure-virtual methods).

+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(HttpUserAgentSettings);

[erikwright (departed), 2012/09/21 15:06:33]

This can be omitted on pure-virtual classes because they can't be constructed
anyways.

+};
+
+// A partial implementation of |HttpUserAgentSettings| that always provides
+// the same constant values for the HTTP Accept-Language and Accept-Charset
+// headers.  Implementors can inherit from this class and implement
+// |GetUserAgent()|.
+class NET_EXPORT ConstHttpAcceptLanguageAndCharset

[erikwright (departed), 2012/09/21 15:06:33]

move to separate file.

+  : public HttpUserAgentSettings {
+ public:
+  virtual const std::string& GetAcceptLanguage() OVERRIDE;
+  virtual const std::string& GetAcceptCharset() OVERRIDE;
+
+ protected:
+  ConstHttpAcceptLanguageAndCharset(const std::string& accept_language,
+                                    const std::string& accept_charset);
+  virtual ~ConstHttpAcceptLanguageAndCharset() {}
+
+ private:
+  const std::string accept_language_;
+  const std::string accept_charset_;
+
+  DISALLOW_COPY_AND_ASSIGN(ConstHttpAcceptLanguageAndCharset);
+};
+
+// An implementation of |HttpUserAgentSettings| that always provides the
+// same constant values for the HTTP Accept-Language, Accept-Charset, and
+// User-Agent headers.
+class NET_EXPORT ConstHttpUserAgentSettings

[erikwright (departed), 2012/09/21 15:06:33]

move to separate file.

+  : public ConstHttpAcceptLanguageAndCharset {
+ public:
+  ConstHttpUserAgentSettings(const std::string& accept_language,
+                             const std::string& accept_charset,
+                             const std::string& user_agent);
+  virtual ~ConstHttpUserAgentSettings() {}
+
+  virtual const std::string& GetUserAgent(const GURL& url) OVERRIDE;
+
+ private:
+  const std::string user_agent_;
+
+  DISALLOW_COPY_AND_ASSIGN(ConstHttpUserAgentSettings);
+};
+
+
 // Subclass to provide application-specific context for URLRequest
 // instances. Note that URLRequestContext typically does not provide storage for
 // these member variables, since they may be shared. For the ones that aren't
@@ -173,21 +238,14 @@ class NET_EXPORT URLRequestContext
   }
 
   // Gets the value of 'Accept-Charset' header field.
-  const std::string& accept_charset() const { return accept_charset_; }
-  void set_accept_charset(const std::string& accept_charset) {
-    accept_charset_ = accept_charset;
-  }
+  const std::string& accept_charset() const;

[erikwright (departed), 2012/09/21 15:06:33]

Group these together with a single "Legacy accessors that delegate to ..."
comment.
Add a TODO(pauljensen): Remove after all clients are updated to directly access
...

 
   // Gets the value of 'Accept-Language' header field.
-  const std::string& accept_language() const { return accept_language_; }
-  void set_accept_language(const std::string& accept_language) {
-    accept_language_ = accept_language;
-  }
+  const std::string& accept_language() const;
 
   // Gets the UA string to use for the given URL.  Pass an invalid URL (such as
-  // GURL()) to get the default UA string.  Subclasses should override this
-  // method to provide a UA string.
-  virtual const std::string& GetUserAgent(const GURL& url) const;
+  // GURL()) to get the default UA string.
+  const std::string& GetUserAgent(const GURL& url) const;
 
   // In general, referrer_charset is not known when URLRequestContext is
   // constructed. So, we need a setter.
@@ -217,6 +275,17 @@ class NET_EXPORT URLRequestContext
 
   void AssertNoURLRequests() const;
 
+  // Set the underlying |HttpUserAgentSettings| implementation that provides
+  // the HTTP Accept-Language, Accept-Charset and User-Agent header values that

[erikwright (departed), 2012/09/21 15:06:33]

Clients should actually access HttpUserAgentSettings directly very soon.

So just remove the bits about accept_language() etc.

+  // are returned by |accept_language|, |accept_charset|, and |GetUserAgent|.
+  // Note: This implementation is not owned by |URLRequestContext|, so it is

[erikwright (departed), 2012/09/21 15:06:33]

The "Note" is not required since it's the same as all other members. If we
weren't removing URLRequestContext ASAP I'd double check that the class comments
say as much, but right now I'm indifferent.

+  // the responsibility of the caller of |set_http_user_agent_settings| to
+  // ensure the implementation outlives the use of this |URLRequestContext|.
+  void set_http_user_agent_settings(
+    HttpUserAgentSettings* http_user_agent_settings) {
+      http_user_agent_settings_ = http_user_agent_settings;
+  }
+
  private:
   // ---------------------------------------------------------------------------
   // Important: When adding any new members below, consider whether they need to
@@ -240,8 +309,6 @@ class NET_EXPORT URLRequestContext
 #if !defined(DISABLE_FTP_SUPPORT)
   scoped_ptr<FtpAuthCache> ftp_auth_cache_;
 #endif
-  std::string accept_language_;
-  std::string accept_charset_;
   // The charset of the referrer where this request comes from. It's not
   // used in communication with a server but is used to construct a suggested
   // filename for file download.
@@ -250,6 +317,7 @@ class NET_EXPORT URLRequestContext
   FtpTransactionFactory* ftp_transaction_factory_;
   const URLRequestJobFactory* job_factory_;
   URLRequestThrottlerManager* throttler_manager_;
+  HttpUserAgentSettings* http_user_agent_settings_;
 
   // ---------------------------------------------------------------------------
   // Important: When adding any new members below, consider whether they need to