Enable forced extension updates on NaCl arch mismatch.

This causes ExtensionUpdater to scan the contents of
installed extensions prior to initiating update queries. If
any extensions are found with a _platform_specific
directory that does NOT contain a subdirectory which
corresponds to the current NaCl arch, that extension is
placed into forced-update mode.

An extension in forced-update mode will be treated as
version 0.0.0.0 when querying the update server.

BUG=409948

Review URL: https://codereview.chromium.org/540673002

Cr-Commit-Position: refs/heads/master@{#293548}

9 files changed, 218 insertions, 49 deletions

diff --git a/chrome/browser/extensions/updater/extension_downloader.cc b/chrome/browser/extensions/updater/extension_downloader.cc
index 264e461..4a0273d 100644
--- a/chrome/browser/extensions/updater/extension_downloader.cc
+++ b/chrome/browser/extensions/updater/extension_downloader.cc
@@ -210,10 +210,17 @@ bool ExtensionDownloader::AddExtension(const Extension& extension,
   if (!ManifestURL::UpdatesFromGallery(&extension))
     update_url_data = delegate_->GetUpdateUrlData(extension.id());
 
-  return AddExtensionData(extension.id(), *extension.version(),
+  std::string install_source;
+  bool force_update = delegate_->ShouldForceUpdate(extension.id(),
+                                                   &install_source);
+  return AddExtensionData(extension.id(),
+                          *extension.version(),
                           extension.GetType(),
                           ManifestURL::GetUpdateURL(&extension),
-                          update_url_data, request_id);
+                          update_url_data,
+                          request_id,
+                          force_update,
+                          install_source);
 }
 
 bool ExtensionDownloader::AddPendingExtension(const std::string& id,
@@ -230,7 +237,9 @@ bool ExtensionDownloader::AddPendingExtension(const std::string& id,
                           Manifest::TYPE_UNKNOWN,
                           update_url,
                           std::string(),
-                          request_id);
+                          request_id,
+                          false,
+                          std::string());
 }
 
 void ExtensionDownloader::StartAllPending(ExtensionCache* cache) {
@@ -273,7 +282,8 @@ void ExtensionDownloader::StartBlacklistUpdate(
                                 version,
                                 &ping_data,
                                 std::string(),
-                                kDefaultInstallSource);
+                                kDefaultInstallSource,
+                                false);
   StartUpdateCheck(blacklist_fetch.Pass());
 }
 
@@ -282,12 +292,15 @@ void ExtensionDownloader::SetWebstoreIdentityProvider(
   identity_provider_.swap(identity_provider);
 }
 
-bool ExtensionDownloader::AddExtensionData(const std::string& id,
-                                           const Version& version,
-                                           Manifest::Type extension_type,
-                                           const GURL& extension_update_url,
-                                           const std::string& update_url_data,
-                                           int request_id) {
+bool ExtensionDownloader::AddExtensionData(
+    const std::string& id,
+    const Version& version,
+    Manifest::Type extension_type,
+    const GURL& extension_update_url,
+    const std::string& update_url_data,
+    int request_id,
+    bool force_update,
+    const std::string& install_source_override) {
   GURL update_url(extension_update_url);
   // Skip extensions with non-empty invalid update URLs.
   if (!update_url.is_empty() && !update_url.is_valid()) {
@@ -353,6 +366,9 @@ bool ExtensionDownloader::AddExtensionData(const std::string& id,
 
     std::string install_source = i == 0 ?
         kDefaultInstallSource : kNotFromWebstoreInstallSource;
+    if (!install_source_override.empty()) {
+      install_source = install_source_override;
+    }
 
     ManifestFetchData::PingData ping_data;
     ManifestFetchData::PingData* optional_ping_data = NULL;
@@ -369,7 +385,8 @@ bool ExtensionDownloader::AddExtensionData(const std::string& id,
       ManifestFetchData* existing_fetch = existing_iter->second.back().get();
       if (existing_fetch->AddExtension(id, version.GetString(),
                                        optional_ping_data, update_url_data,
-                                       install_source)) {
+                                       install_source,
+                                       force_update)) {
         added = true;
       }
     }
@@ -383,7 +400,8 @@ bool ExtensionDownloader::AddExtensionData(const std::string& id,
       added = fetch->AddExtension(id, version.GetString(),
                                   optional_ping_data,
                                   update_url_data,
-                                  install_source);
+                                  install_source,
+                                  force_update);
       DCHECK(added);
     }
   }
@@ -639,12 +657,14 @@ void ExtensionDownloader::DetermineUpdates(
 
       VLOG(2) << id << " is at '" << version << "'";
 
-      Version existing_version(version);
-      Version update_version(update->version);
-
-      if (!update_version.IsValid() ||
-          update_version.CompareTo(existing_version) <= 0) {
-        continue;
+      // We should skip the version check if update was forced.
+      if (!fetch_data.DidForceUpdate(id)) {
+        Version existing_version(version);
+        Version update_version(update->version);
+        if (!update_version.IsValid() ||
+            update_version.CompareTo(existing_version) <= 0) {
+          continue;
+        }
       }
     }
 
diff --git a/chrome/browser/extensions/updater/extension_downloader.h b/chrome/browser/extensions/updater/extension_downloader.h
index a040986..813a400 100644
--- a/chrome/browser/extensions/updater/extension_downloader.h
+++ b/chrome/browser/extensions/updater/extension_downloader.h
@@ -166,7 +166,9 @@ class ExtensionDownloader
                         Manifest::Type extension_type,
                         const GURL& extension_update_url,
                         const std::string& update_url_data,
-                        int request_id);
+                        int request_id,
+                        bool force_update,
+                        const std::string& install_source_override);
 
   // Adds all recorded stats taken so far to histogram counts.
   void ReportStats() const;
diff --git a/chrome/browser/extensions/updater/extension_downloader_delegate.cc b/chrome/browser/extensions/updater/extension_downloader_delegate.cc
index 2cddee3..ab3f734 100644
--- a/chrome/browser/extensions/updater/extension_downloader_delegate.cc
+++ b/chrome/browser/extensions/updater/extension_downloader_delegate.cc
@@ -32,4 +32,10 @@ std::string ExtensionDownloaderDelegate::GetUpdateUrlData(
   return std::string();
 }
 
+bool ExtensionDownloaderDelegate::ShouldForceUpdate(
+    const std::string& id,
+    std::string* source) {
+  return false;
+}
+
 }  // namespace extensions
diff --git a/chrome/browser/extensions/updater/extension_downloader_delegate.h b/chrome/browser/extensions/updater/extension_downloader_delegate.h
index a9914c7..03b5ac6 100644
--- a/chrome/browser/extensions/updater/extension_downloader_delegate.h
+++ b/chrome/browser/extensions/updater/extension_downloader_delegate.h
@@ -111,6 +111,13 @@ class ExtensionDownloaderDelegate {
   // that extension is not installed.
   virtual bool GetExtensionExistingVersion(const std::string& id,
                                            std::string* version) = 0;
+
+  // Determines if a given extension should be forced to update and (if so)
+  // what the source of this forcing is (i.e. what string will be passed
+  // in |installsource| as part of the update query parameters). The default
+  // implementation always returns |false|.
+  virtual bool ShouldForceUpdate(const std::string& id,
+                                 std::string* source);
 };
 
 }  // namespace extensions
diff --git a/chrome/browser/extensions/updater/extension_updater.cc b/chrome/browser/extensions/updater/extension_updater.cc
index 1c64bc9..3cd89a2 100644
--- a/chrome/browser/extensions/updater/extension_updater.cc
+++ b/chrome/browser/extensions/updater/extension_updater.cc
@@ -8,6 +8,8 @@
 #include <set>
 
 #include "base/bind.h"
+#include "base/files/file_enumerator.h"
+#include "base/files/file_util.h"
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
 #include "base/prefs/pref_service.h"
@@ -22,6 +24,7 @@
 #include "chrome/browser/extensions/pending_extension_manager.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/common/pref_names.h"
+#include "components/omaha_query_params/omaha_query_params.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/notification_details.h"
 #include "content/public/browser/notification_service.h"
@@ -40,6 +43,9 @@ using base::RandInt;
 using base::Time;
 using base::TimeDelta;
 using content::BrowserThread;
+using extensions::Extension;
+using extensions::ExtensionSet;
+using omaha_query_params::OmahaQueryParams;
 
 typedef extensions::ExtensionDownloaderDelegate::Error Error;
 typedef extensions::ExtensionDownloaderDelegate::PingResult PingResult;
@@ -60,6 +66,10 @@ const int kMaxUpdateFrequencySeconds = 60 * 60 * 24 * 7;  // 7 days
 // checks.
 const int kMinUpdateThrottleTime = 5;
 
+// The installsource query parameter to use when forcing updates due to NaCl
+// arch mismatch.
+const char kWrongMultiCrxInstallSource[] = "wrong_multi_crx";
+
 // When we've computed a days value, we want to make sure we don't send a
 // negative value (due to the system clock being set backwards, etc.), since -1
 // is a special sentinel value that means "never pinged", and other negative
@@ -88,6 +98,73 @@ int CalculateActivePingDays(const Time& last_active_ping_day,
   return SanitizeDays((Time::Now() - last_active_ping_day).InDays());
 }
 
+void RespondWithForcedUpdates(
+    const base::Callback<void(const std::set<std::string>&)>& callback,
+    scoped_ptr<std::set<std::string> > forced_updates) {
+  callback.Run(*forced_updates.get());
+}
+
+void DetermineForcedUpdatesOnBlockingPool(
+    scoped_ptr<std::vector<scoped_refptr<const Extension> > > extensions,
+    const base::Callback<void(const std::set<std::string>&)>& callback) {
+  scoped_ptr<std::set<std::string> > forced_updates(
+      new std::set<std::string>());
+  DCHECK(!BrowserThread::CurrentlyOn(BrowserThread::UI));
+  for (std::vector<scoped_refptr<const Extension> >::const_iterator iter =
+          extensions->begin();
+       iter != extensions->end();
+       ++iter) {
+    scoped_refptr<const Extension> extension = *iter;
+    base::FilePath platform_specific_path = extension->path().Append(
+        extensions::kPlatformSpecificFolder);
+    if (base::PathExists(platform_specific_path)) {
+      bool force = true;
+      base::FileEnumerator all_archs(platform_specific_path,
+                                     false,
+                                     base::FileEnumerator::DIRECTORIES);
+      base::FilePath arch;
+      while (!(arch = all_archs.Next()).empty()) {
+        std::string arch_name = arch.BaseName().AsUTF8Unsafe();
+        std::replace(arch_name.begin(), arch_name.end(), '_', '-');
+        if (arch_name == OmahaQueryParams::GetNaclArch())
+          force = false;
+      }
+
+      if (force)
+        forced_updates->insert(extension->id());
+   }
+  }
+  BrowserThread::PostTask(
+      BrowserThread::UI,
+      FROM_HERE,
+      base::Bind(&RespondWithForcedUpdates,
+                 callback,
+                 base::Passed(&forced_updates)));
+}
+
+void CollectExtensionsFromSet(
+    const ExtensionSet& extensions,
+    std::vector<scoped_refptr<const Extension> >* paths) {
+  std::copy(extensions.begin(), extensions.end(), std::back_inserter(*paths));
+}
+
+void DetermineForcedUpdates(
+    content::BrowserContext* browser_context,
+    const base::Callback<void(const std::set<std::string>&)>& callback) {
+  scoped_ptr<std::vector<scoped_refptr<const Extension> > > extensions(
+      new std::vector<scoped_refptr<const Extension> >());
+  const extensions::ExtensionRegistry* registry =
+      extensions::ExtensionRegistry::Get(browser_context);
+  scoped_ptr<ExtensionSet> installed_extensions =
+      registry->GenerateInstalledExtensionsSet();
+  CollectExtensionsFromSet(*installed_extensions.get(), extensions.get());
+  BrowserThread::PostBlockingPoolTask(
+      FROM_HERE,
+      base::Bind(&DetermineForcedUpdatesOnBlockingPool,
+                 base::Passed(&extensions),
+                 callback));
+}
+
 }  // namespace
 
 namespace extensions {
@@ -335,6 +412,16 @@ void ExtensionUpdater::AddToDownloader(
 }
 
 void ExtensionUpdater::CheckNow(const CheckParams& params) {
+  DetermineForcedUpdates(
+      profile_,
+      base::Bind(&ExtensionUpdater::OnForcedUpdatesDetermined,
+                 weak_ptr_factory_.GetWeakPtr(),
+                 params));
+}
+
+void ExtensionUpdater::OnForcedUpdatesDetermined(
+    const CheckParams& params,
+    const std::set<std::string>& forced_updates) {
   int request_id = next_request_id_++;
 
   VLOG(2) << "Starting update check " << request_id;
@@ -349,6 +436,8 @@ void ExtensionUpdater::CheckNow(const CheckParams& params) {
 
   EnsureDownloaderCreated();
 
+  forced_updates_ = forced_updates;
+
   // Add fetch records for extensions that should be fetched by an update URL.
   // These extensions are not yet installed. They come from group policy
   // and external install sources.
@@ -536,6 +625,18 @@ bool ExtensionUpdater::GetExtensionExistingVersion(const std::string& id,
   return true;
 }
 
+bool ExtensionUpdater::ShouldForceUpdate(
+    const std::string& extension_id,
+    std::string* source) {
+  bool force = forced_updates_.find(extension_id) != forced_updates_.end();
+  // Currently the only reason to force is a NaCl arch mismatch with the
+  // installed extension contents.
+  if (force) {
+    *source = kWrongMultiCrxInstallSource;
+  }
+  return force;
+}
+
 void ExtensionUpdater::UpdatePingData(const std::string& id,
                                       const PingResult& ping_result) {
   DCHECK(alive_);
diff --git a/chrome/browser/extensions/updater/extension_updater.h b/chrome/browser/extensions/updater/extension_updater.h
index 29faf71..88401da 100644
--- a/chrome/browser/extensions/updater/extension_updater.h
+++ b/chrome/browser/extensions/updater/extension_updater.h
@@ -157,6 +157,11 @@ class ExtensionUpdater : public ExtensionDownloaderDelegate,
 
   struct ThrottleInfo;
 
+  // Callback used to continue CheckNow after determining which extensions
+  // should be force-updated.
+  void OnForcedUpdatesDetermined(const CheckParams& params,
+                                 const std::set<std::string>& forced_updates);
+
   // Ensure that we have a valid ExtensionDownloader instance referenced by
   // |downloader|.
   void EnsureDownloaderCreated();
@@ -188,7 +193,6 @@ class ExtensionUpdater : public ExtensionDownloaderDelegate,
       Error error,
       const PingResult& ping,
       const std::set<int>& request_ids) OVERRIDE;
-
   virtual void OnExtensionDownloadFinished(
       const std::string& id,
       const base::FilePath& path,
@@ -197,25 +201,15 @@ class ExtensionUpdater : public ExtensionDownloaderDelegate,
       const std::string& version,
       const PingResult& ping,
       const std::set<int>& request_id) OVERRIDE;
-
-  // Implementation of ExtensionRegistryObserver.
-  virtual void OnExtensionWillBeInstalled(
-      content::BrowserContext* browser_context,
-      const Extension* extension,
-      bool is_update,
-      bool from_ephemeral,
-      const std::string& old_name) OVERRIDE;
-
   virtual bool GetPingDataForExtension(
       const std::string& id,
       ManifestFetchData::PingData* ping_data) OVERRIDE;
-
   virtual std::string GetUpdateUrlData(const std::string& id) OVERRIDE;
-
   virtual bool IsExtensionPending(const std::string& id) OVERRIDE;
-
   virtual bool GetExtensionExistingVersion(const std::string& id,
                                            std::string* version) OVERRIDE;
+  virtual bool ShouldForceUpdate(const std::string& extension_id,
+                                 std::string* source) OVERRIDE;
 
   void UpdatePingData(const std::string& id, const PingResult& ping_result);
 
@@ -227,6 +221,14 @@ class ExtensionUpdater : public ExtensionDownloaderDelegate,
                        const content::NotificationSource& source,
                        const content::NotificationDetails& details) OVERRIDE;
 
+  // Implementation of ExtensionRegistryObserver.
+  virtual void OnExtensionWillBeInstalled(
+      content::BrowserContext* browser_context,
+      const Extension* extension,
+      bool is_update,
+      bool from_ephemeral,
+      const std::string& old_name) OVERRIDE;
+
   // Send a notification that update checks are starting.
   void NotifyStarted();
 
@@ -284,6 +286,10 @@ class ExtensionUpdater : public ExtensionDownloaderDelegate,
   // checks to prevent too many requests from being made.
   std::map<std::string, ThrottleInfo> throttle_info_;
 
+  // Keeps track of extensions (by ID) whose update should be forced during the
+  // next update check.
+  std::set<std::string> forced_updates_;
+
   DISALLOW_COPY_AND_ASSIGN(ExtensionUpdater);
 };
 
diff --git a/chrome/browser/extensions/updater/extension_updater_unittest.cc b/chrome/browser/extensions/updater/extension_updater_unittest.cc
index 4a7375f..1f6f7d6 100644
--- a/chrome/browser/extensions/updater/extension_updater_unittest.cc
+++ b/chrome/browser/extensions/updater/extension_updater_unittest.cc
@@ -613,6 +613,7 @@ class ExtensionUpdaterTest : public testing::Test {
     EXPECT_TRUE(updater->timer_.IsRunning());
     updater->timer_.Stop();
     updater->TimerFired();
+    content::RunAllBlockingPoolTasksUntilIdle();
   }
 
   // Adds a Result with the given data to results.
@@ -703,7 +704,7 @@ class ExtensionUpdaterTest : public testing::Test {
     // option to appear in the x= parameter.
     ManifestFetchData fetch_data(GURL("http://localhost/foo"), 0);
     fetch_data.AddExtension(
-        id, version, &kNeverPingedData, std::string(), std::string());
+        id, version, &kNeverPingedData, std::string(), std::string(), false);
 
     std::map<std::string, std::string> params;
     VerifyQueryAndExtractParameters(fetch_data.full_url().query(), &params);
@@ -720,7 +721,7 @@ class ExtensionUpdaterTest : public testing::Test {
     // option to appear in the x= parameter.
     ManifestFetchData fetch_data(GURL("http://localhost/foo"), 0);
     fetch_data.AddExtension(
-        id, version, &kNeverPingedData, "bar", std::string());
+        id, version, &kNeverPingedData, "bar", std::string(), false);
     std::map<std::string, std::string> params;
     VerifyQueryAndExtractParameters(fetch_data.full_url().query(), &params);
     EXPECT_EQ(id, params["id"]);
@@ -736,7 +737,7 @@ class ExtensionUpdaterTest : public testing::Test {
     // option to appear in the x= parameter.
     ManifestFetchData fetch_data(GURL("http://localhost/foo"), 0);
     fetch_data.AddExtension(
-        id, version, &kNeverPingedData, "a=1&b=2&c", std::string());
+        id, version, &kNeverPingedData, "a=1&b=2&c", std::string(), false);
     std::map<std::string, std::string> params;
     VerifyQueryAndExtractParameters(fetch_data.full_url().query(), &params);
     EXPECT_EQ(id, params["id"]);
@@ -780,7 +781,7 @@ class ExtensionUpdaterTest : public testing::Test {
     // Make sure that an installsource= appears in the x= parameter.
     ManifestFetchData fetch_data(GURL("http://localhost/foo"), 0);
     fetch_data.AddExtension(id, version, &kNeverPingedData,
-                            kEmptyUpdateUrlData, install_source);
+                            kEmptyUpdateUrlData, install_source, false);
     std::map<std::string, std::string> params;
     VerifyQueryAndExtractParameters(fetch_data.full_url().query(), &params);
     EXPECT_EQ(id, params["id"]);
@@ -806,10 +807,12 @@ class ExtensionUpdaterTest : public testing::Test {
     const std::string id1 = crx_file::id_util::GenerateId("1");
     const std::string id2 = crx_file::id_util::GenerateId("2");
     fetch_data.AddExtension(
-        id1, "1.0.0.0", &kNeverPingedData, kEmptyUpdateUrlData, std::string());
+        id1, "1.0.0.0", &kNeverPingedData, kEmptyUpdateUrlData, std::string(),
+        false);
     AddParseResult(id1, "1.1", "http://localhost/e1_1.1.crx", &updates);
     fetch_data.AddExtension(
-        id2, "2.0.0.0", &kNeverPingedData, kEmptyUpdateUrlData, std::string());
+        id2, "2.0.0.0", &kNeverPingedData, kEmptyUpdateUrlData, std::string(),
+        false);
     AddParseResult(id2, "2.0.0.0", "http://localhost/e2_2.0.crx", &updates);
 
     EXPECT_CALL(delegate, IsExtensionPending(_)).WillRepeatedly(Return(false));
@@ -850,7 +853,8 @@ class ExtensionUpdaterTest : public testing::Test {
                               "1.0.0.0",
                               &kNeverPingedData,
                               kEmptyUpdateUrlData,
-                              std::string());
+                              std::string(),
+                              false);
       AddParseResult(*it, "1.1", "http://localhost/e1_1.1.crx", &updates);
     }
 
@@ -884,13 +888,13 @@ class ExtensionUpdaterTest : public testing::Test {
     scoped_ptr<ManifestFetchData> fetch4(new ManifestFetchData(kUpdateUrl, 0));
     ManifestFetchData::PingData zeroDays(0, 0, true);
     fetch1->AddExtension(
-        "1111", "1.0", &zeroDays, kEmptyUpdateUrlData, std::string());
+        "1111", "1.0", &zeroDays, kEmptyUpdateUrlData, std::string(), false);
     fetch2->AddExtension(
-        "2222", "2.0", &zeroDays, kEmptyUpdateUrlData, std::string());
+        "2222", "2.0", &zeroDays, kEmptyUpdateUrlData, std::string(), false);
     fetch3->AddExtension(
-        "3333", "3.0", &zeroDays, kEmptyUpdateUrlData, std::string());
+        "3333", "3.0", &zeroDays, kEmptyUpdateUrlData, std::string(), false);
     fetch4->AddExtension(
-        "4444", "4.0", &zeroDays, kEmptyUpdateUrlData, std::string());
+        "4444", "4.0", &zeroDays, kEmptyUpdateUrlData, std::string(), false);
 
     // This will start the first fetcher and queue the others. The next in queue
     // is started as each fetcher receives its response. Note that the fetchers
@@ -1021,7 +1025,7 @@ class ExtensionUpdaterTest : public testing::Test {
     scoped_ptr<ManifestFetchData> fetch(new ManifestFetchData(kUpdateUrl, 0));
     ManifestFetchData::PingData zeroDays(0, 0, true);
     fetch->AddExtension(
-        "1111", "1.0", &zeroDays, kEmptyUpdateUrlData, std::string());
+        "1111", "1.0", &zeroDays, kEmptyUpdateUrlData, std::string(), false);
 
     // This will start the first fetcher.
     downloader.StartUpdateCheck(fetch.Pass());
@@ -1049,7 +1053,7 @@ class ExtensionUpdaterTest : public testing::Test {
     // should not retry.
     fetch.reset(new ManifestFetchData(kUpdateUrl, 0));
     fetch->AddExtension(
-        "1111", "1.0", &zeroDays, kEmptyUpdateUrlData, std::string());
+        "1111", "1.0", &zeroDays, kEmptyUpdateUrlData, std::string(), false);
 
     // This will start the first fetcher.
     downloader.StartUpdateCheck(fetch.Pass());
@@ -1604,6 +1608,7 @@ class ExtensionUpdaterTest : public testing::Test {
     ExtensionUpdater::CheckParams params;
     updater.Start();
     updater.CheckNow(params);
+    content::RunAllBlockingPoolTasksUntilIdle();
 
     // Make the updater do manifest fetching, and note the urls it tries to
     // fetch.
@@ -1707,7 +1712,8 @@ class ExtensionUpdaterTest : public testing::Test {
                             extension->VersionString(),
                             &kNeverPingedData,
                             kEmptyUpdateUrlData,
-                            std::string());
+                            std::string(),
+                            false);
     UpdateManifest::Results results;
     results.daystart_elapsed_seconds = 750;
 
@@ -1905,6 +1911,7 @@ TEST_F(ExtensionUpdaterTest, TestNonAutoUpdateableLocations) {
   ExtensionUpdater::CheckParams params;
   updater.Start();
   updater.CheckNow(params);
+  content::RunAllBlockingPoolTasksUntilIdle();
 }
 
 TEST_F(ExtensionUpdaterTest, TestUpdatingDisabledExtensions) {
@@ -1943,6 +1950,7 @@ TEST_F(ExtensionUpdaterTest, TestUpdatingDisabledExtensions) {
   ExtensionUpdater::CheckParams params;
   updater.Start();
   updater.CheckNow(params);
+  content::RunAllBlockingPoolTasksUntilIdle();
 }
 
 TEST_F(ExtensionUpdaterTest, TestManifestFetchesBuilderAddExtension) {
diff --git a/chrome/browser/extensions/updater/manifest_fetch_data.cc b/chrome/browser/extensions/updater/manifest_fetch_data.cc
index 8ed4fe0..dafbdf8 100644
--- a/chrome/browser/extensions/updater/manifest_fetch_data.cc
+++ b/chrome/browser/extensions/updater/manifest_fetch_data.cc
@@ -67,16 +67,24 @@ bool ManifestFetchData::AddExtension(const std::string& id,
                                      const std::string& version,
                                      const PingData* ping_data,
                                      const std::string& update_url_data,
-                                     const std::string& install_source) {
+                                     const std::string& install_source,
+                                     bool force_update) {
   if (extension_ids_.find(id) != extension_ids_.end()) {
     NOTREACHED() << "Duplicate extension id " << id;
     return false;
   }
 
+  if (force_update)
+    forced_updates_.insert(id);
+
+  // If we want to force an update, we send 0.0.0.0 as the installed version
+  // number.
+  const std::string installed_version = force_update ? "0.0.0.0" : version;
+
   // Compute the string we'd append onto the full_url_, and see if it fits.
   std::vector<std::string> parts;
   parts.push_back("id=" + id);
-  parts.push_back("v=" + version);
+  parts.push_back("v=" + installed_version);
   if (!install_source.empty())
     parts.push_back("installsource=" + install_source);
   parts.push_back("uc");
@@ -163,4 +171,8 @@ void ManifestFetchData::Merge(const ManifestFetchData& other) {
   request_ids_.insert(other.request_ids_.begin(), other.request_ids_.end());
 }
 
+bool ManifestFetchData::DidForceUpdate(const std::string& extension_id) const {
+  return forced_updates_.find(extension_id) != forced_updates_.end();
+}
+
 }  // namespace extensions
diff --git a/chrome/browser/extensions/updater/manifest_fetch_data.h b/chrome/browser/extensions/updater/manifest_fetch_data.h
index a7eab99..36a77c8 100644
--- a/chrome/browser/extensions/updater/manifest_fetch_data.h
+++ b/chrome/browser/extensions/updater/manifest_fetch_data.h
@@ -56,7 +56,8 @@ class ManifestFetchData {
                     const std::string& version,
                     const PingData* ping_data,
                     const std::string& update_url_data,
-                    const std::string& install_source);
+                    const std::string& install_source,
+                    bool force_update);
 
   const GURL& base_url() const { return base_url_; }
   const GURL& full_url() const { return full_url_; }
@@ -76,6 +77,9 @@ class ManifestFetchData {
   // to this ManifestFetchData).
   void Merge(const ManifestFetchData& other);
 
+  // Returns |true| if a given extension was forced to update.
+  bool DidForceUpdate(const std::string& extension_id) const;
+
  private:
   // The set of extension id's for this ManifestFetchData.
   std::set<std::string> extension_ids_;
@@ -96,6 +100,9 @@ class ManifestFetchData {
   // one ManifestFetchData.
   std::set<int> request_ids_;
 
+  // The set of extension IDs for which this fetch forced a CRX update.
+  std::set<std::string> forced_updates_;
+
   DISALLOW_COPY_AND_ASSIGN(ManifestFetchData);
 };