Experimental integration of delta compression content encoding

The command line option "sdch-enable" enables support of sdch
and automtic lazy download of dictionaries.  Optionally it
can select a singular domain to work from.

By default, all domains are enabled when the flag is used.
"-sdch-enable=".google.com"  Enables it only for Google.

When the switch is not set on the command line, all this
code is completely disabled.

Still TBD:
a) Finish implementation of security details (much of it is in place)
b) Add tests for security details.


r=huanr,ajenjo,kmixter

Review URL: http://codereview.chromium.org/461

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@2443 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 130 insertions, 0 deletions

diff --git a/chrome/browser/browser.vcproj b/chrome/browser/browser.vcproj
index fc3c31b..e87a3e0 100644
--- a/chrome/browser/browser.vcproj
+++ b/chrome/browser/browser.vcproj
@@ -1861,6 +1861,14 @@
 				RelativePath=".\net\dns_slave.h"
 				>
 			</File>
+			<File
+				RelativePath=".\net\sdch_dictionary_fetcher.cc"
+				>
+			</File>
+			<File
+				RelativePath=".\net\sdch_dictionary_fetcher.h"
+				>
+			</File>
 		</Filter>
 		<Filter
 			Name="RLZ"
diff --git a/chrome/browser/browser_main.cc b/chrome/browser/browser_main.cc
index 15703a2..fbb216a9 100644
--- a/chrome/browser/browser_main.cc
+++ b/chrome/browser/browser_main.cc
@@ -30,6 +30,7 @@
 #include "chrome/browser/jankometer.h"
 #include "chrome/browser/metrics_service.h"
 #include "chrome/browser/net/dns_global.h"
+#include "chrome/browser/net/sdch_dictionary_fetcher.h"
 #include "chrome/browser/plugin_service.h"
 #include "chrome/browser/printing/print_job_manager.h"
 #include "chrome/browser/rlz/rlz.h"
@@ -53,6 +54,7 @@
 #include "net/base/net_module.h"
 #include "net/base/net_resources.h"
 #include "net/base/net_util.h"
+#include "net/base/sdch_manager.h"
 #include "net/base/winsock_init.h"
 #include "net/http/http_network_layer.h"
 
@@ -475,6 +477,15 @@ int BrowserMain(CommandLine &parsed_command_line, int show_command,
   // Initialize the CertStore.
   CertStore::Initialize();
 
+  // Prepare for memory caching of SDCH dictionaries.
+  SdchManager sdch_manager;  // Construct singleton database.
+  if (parsed_command_line.HasSwitch(switches::kSdchFilter)) {
+    sdch_manager.set_sdch_fetcher(new SdchDictionaryFetcher);
+    std::wstring switch_domain =
+        parsed_command_line.GetSwitchValue(switches::kSdchFilter);
+    sdch_manager.enable_sdch_support(WideToASCII(switch_domain));
+  }
+
   MetricsService* metrics = NULL;
   if (!parsed_command_line.HasSwitch(switches::kDisableMetrics)) {
     if (parsed_command_line.HasSwitch(switches::kDisableMetricsReporting)) {
diff --git a/chrome/browser/net/sdch_dictionary_fetcher.cc b/chrome/browser/net/sdch_dictionary_fetcher.cc
new file mode 100644
index 0000000..1b5c21c
--- /dev/null
+++ b/chrome/browser/net/sdch_dictionary_fetcher.cc
@@ -0,0 +1,45 @@
+// Copyright (c) 2006-2008 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/net/sdch_dictionary_fetcher.h"
+#include "chrome/browser/profile.h"
+
+void SdchDictionaryFetcher::Schedule(const GURL& dictionary_url) {
+  fetch_queue_.push(dictionary_url);
+  ScheduleDelayedRun();
+}
+
+// TODO(jar): If QOS low priority is supported, switch to using that instead of
+// just waiting to do the fetch.
+void SdchDictionaryFetcher::ScheduleDelayedRun() {
+  if (fetch_queue_.empty() || current_fetch_.get() || task_is_pending_)
+    return;
+  MessageLoop::current()->PostDelayedTask(FROM_HERE,
+      method_factory_.NewRunnableMethod(&SdchDictionaryFetcher::StartFetching),
+      kMsDelayFromRequestTillDownload);
+  task_is_pending_ = true;
+}
+
+void SdchDictionaryFetcher::StartFetching() {
+  DCHECK(task_is_pending_);
+  task_is_pending_ = false;
+
+  current_fetch_.reset(new URLFetcher(fetch_queue_.front(), URLFetcher::GET,
+                                      this));
+  fetch_queue_.pop();
+  current_fetch_->set_request_context(Profile::GetDefaultRequestContext());
+  current_fetch_->Start();
+}
+
+void SdchDictionaryFetcher::OnURLFetchComplete(const URLFetcher* source,
+                                               const GURL& url,
+                                               const URLRequestStatus& status,
+                                               int response_code,
+                                               const ResponseCookies& cookies,
+                                               const std::string& data) {
+  if (200 == response_code)
+    SdchManager::Global()->AddSdchDictionary(data, url);
+  current_fetch_.reset(NULL);
+  ScheduleDelayedRun();
+}
diff --git a/chrome/browser/net/sdch_dictionary_fetcher.h b/chrome/browser/net/sdch_dictionary_fetcher.h
new file mode 100644
index 0000000..34d3f28
--- /dev/null
+++ b/chrome/browser/net/sdch_dictionary_fetcher.h
@@ -0,0 +1,66 @@
+// Copyright (c) 2006-2008 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.
+
+// Support modularity by calling to load a new SDCH filter dictionary.
+// Note that this sort of calling can't be done in the /net directory, as it has
+// no concept of the HTTP cache (which is only visible at the browser level).
+
+#ifndef CHROME_BROWSER_NET_SDCH_DICTIONARY_FETCHER_H_
+#define CHROME_BROWSER_NET_SDCH_DICTIONARY_FETCHER_H_
+
+#include <queue>
+#include <string>
+
+#include "base/task.h"
+#include "chrome/browser/url_fetcher.h"
+#include "net/base/sdch_manager.h"
+
+class SdchDictionaryFetcher : public URLFetcher::Delegate,
+                              public SdchFetcher {
+ public:
+  #pragma warning(suppress: 4355)  // OK to pass "this" here.
+  SdchDictionaryFetcher() : method_factory_(this), task_is_pending_(false) {}
+  virtual ~SdchDictionaryFetcher() {}
+
+  // Implementation of SdchFetcher class.
+  // This method gets the requested dictionary, and then calls back into the
+  // SdchManager class with the dictionary's text.
+  virtual void Schedule(const GURL& dictionary_url);
+
+ private:
+  // Delay between Schedule and actual download.
+  static const int kMsDelayFromRequestTillDownload = 15000;
+
+  // Ensure the download after the above delay.
+  void ScheduleDelayedRun();
+
+  // Make sure we're processing (or waiting for) the the arrival of the next URL
+  // in the  |fetch_queue_|.
+  void StartFetching();
+
+  // Implementation of URLFetcher::Delegate. Called after transmission
+  // completes (either successfully or with failure).
+  virtual void OnURLFetchComplete(const URLFetcher* source,
+                                  const GURL& url,
+                                  const URLRequestStatus& status,
+                                  int response_code,
+                                  const ResponseCookies& cookies,
+                                  const std::string& data);
+
+  // A queue of URLs that are being used to download dictionaries.
+  std::queue<GURL> fetch_queue_;
+  // The currently outstanding URL fetch of a dicitonary.
+  // If this is null, then there is no outstanding request.
+  scoped_ptr<URLFetcher> current_fetch_;
+
+  // Always spread out the dictionary fetches, so that they don't steal
+  // bandwidth from the actual page load.  Create delayed tasks to spread out
+  // the download.
+  ScopedRunnableMethodFactory<SdchDictionaryFetcher> method_factory_;
+  bool task_is_pending_;
+
+  DISALLOW_COPY_AND_ASSIGN(SdchDictionaryFetcher);
+};
+
+#endif  // CHROME_BROWSER_NET_SDCH_DICTIONARY_FETCHER_H_