Update prerender policy for custom tabs

- Explicitly early return if the prerender privacy setting is set to off
- If the setting is on then prerendering on mobile is off by default
- Add calls and session params to override the above default if needed

BUG=592635

Review URL: https://codereview.chromium.org/1830653003 .

Cr-Commit-Position: refs/branch-heads/2661@{#365}
Cr-Branched-From: ef6f6ae5e4c96622286b563658d5cd62a6cf1197-refs/heads/master@{#378081}

15 files changed, 194 insertions, 30 deletions

diff --git a/chrome/android/java/src/org/chromium/chrome/browser/WarmupManager.java b/chrome/android/java/src/org/chromium/chrome/browser/WarmupManager.java
index 7747d58..bb235d8 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/WarmupManager.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/WarmupManager.java
@@ -131,7 +131,7 @@ public final class WarmupManager {
         }
 
         mPrerenderedWebContents = mExternalPrerenderHandler.addPrerender(
-                Profile.getLastUsedProfile(), url, referrer, widthPix, heightPix);
+                Profile.getLastUsedProfile(), url, referrer, widthPix, heightPix, false);
         if (mPrerenderedWebContents != null) mPrerendered = true;
     }
 
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/customtabs/ClientManager.java b/chrome/android/java/src/org/chromium/chrome/browser/customtabs/ClientManager.java
index 5624ca4..4cadc39 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/customtabs/ClientManager.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/customtabs/ClientManager.java
@@ -54,6 +54,7 @@ class ClientManager {
         public final IBinder.DeathRecipient deathRecipient;
         public boolean mIgnoreFragments;
         private boolean mShouldHideDomain;
+        private boolean mShouldPrerenderOnCellular;
         private ServiceConnection mKeepAliveConnection;
         private String mPredictedUrl;
         private long mLastMayLaunchUrlTimestamp;
@@ -270,7 +271,23 @@ class ClientManager {
     /** Sets whether the fragment should be ignored for prerender matching. */
     public synchronized void setIgnoreFragmentsForSession(IBinder session, boolean value) {
         SessionParams params = mSessionParams.get(session);
-        params.mIgnoreFragments = value;
+        if (params != null) params.mIgnoreFragments = value;
+    }
+
+    /**
+     * @return Whether prerender should be turned on for cellular networks for given session.
+     */
+    public synchronized boolean shouldPrerenderOnCellularForSession(IBinder session) {
+        SessionParams params = mSessionParams.get(session);
+        return params != null ? params.mShouldPrerenderOnCellular : false;
+    }
+
+    /**
+     * Sets whether prerender should be turned on for mobile networks for given session.
+     */
+    public synchronized void setPrerenderCellularForSession(IBinder session, boolean prerender) {
+        SessionParams params = mSessionParams.get(session);
+        if (params != null) params.mShouldPrerenderOnCellular = prerender;
     }
 
     /** Tries to bind to a client to keep it alive, and returns true for success. */
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabsConnection.java b/chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabsConnection.java
index 5181588..8ed88b9 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabsConnection.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabsConnection.java
@@ -44,6 +44,7 @@ import org.chromium.chrome.browser.WarmupManager;
 import org.chromium.chrome.browser.WebContentsFactory;
 import org.chromium.chrome.browser.device.DeviceClassManager;
 import org.chromium.chrome.browser.init.ChromeBrowserInitializer;
+import org.chromium.chrome.browser.preferences.privacy.PrivacyPreferencesManager;
 import org.chromium.chrome.browser.prerender.ExternalPrerenderHandler;
 import org.chromium.chrome.browser.profiles.Profile;
 import org.chromium.chrome.browser.util.IntentUtils;
@@ -284,7 +285,7 @@ public class CustomTabsConnection extends ICustomTabsService.Stub {
         WarmupManager.getInstance().maybePreconnectUrlAndSubResources(
                 Profile.getLastUsedProfile(), url);
         boolean didStartPrerender = false;
-        if (!noPrerendering && mayPrerender()) {
+        if (!noPrerendering && mayPrerender(session)) {
             didStartPrerender = prerenderUrl(session, url, extras, uid);
         }
         preconnectUrls(otherLikelyBundles);
@@ -510,6 +511,11 @@ public class CustomTabsConnection extends ICustomTabsService.Stub {
         return mClientManager.shouldHideDomainForSession(session);
     }
 
+    /** @see ClientManager#shouldPrerenderOnCellularForSession(IBinder) */
+    public boolean shouldPrerenderOnCellularForSession(IBinder session) {
+        return mClientManager.shouldPrerenderOnCellularForSession(session);
+    }
+
     /** See {@link ClientManager#getClientPackageNameForSession(IBinder)} */
     public String getClientPackageNameForSession(IBinder session) {
         return mClientManager.getClientPackageNameForSession(session);
@@ -654,13 +660,14 @@ public class CustomTabsConnection extends ICustomTabsService.Stub {
         mClientManager.cleanupAll();
     }
 
-    private boolean mayPrerender() {
+    private boolean mayPrerender(IBinder session) {
         if (FieldTrialList.findFullName("CustomTabs").equals("DisablePrerender")) return false;
         if (!DeviceClassManager.enablePrerendering()) return false;
+        if (!PrivacyPreferencesManager.getInstance(mApplication).shouldPrerender()) return false;
         ConnectivityManager cm =
                 (ConnectivityManager) mApplication.getApplicationContext().getSystemService(
                         Context.CONNECTIVITY_SERVICE);
-        return !cm.isActiveNetworkMetered();
+        return !cm.isActiveNetworkMetered() || shouldPrerenderOnCellularForSession(session);
     }
 
     /** Cancels a prerender for a given session, or any session if null. */
@@ -689,7 +696,7 @@ public class CustomTabsConnection extends ICustomTabsService.Stub {
         // limitation, or remove ChromePrerenderService.
         WarmupManager.getInstance().disallowPrerendering();
         // Ignores mayPrerender() for an empty URL, since it cancels an existing prerender.
-        if (!mayPrerender() && !TextUtils.isEmpty(url)) return false;
+        if (!mayPrerender(session) && !TextUtils.isEmpty(url)) return false;
         if (!mWarmupHasBeenCalled.get()) return false;
         // Last one wins and cancels the previous prerender.
         cancelPrerender(null);
@@ -713,7 +720,8 @@ public class CustomTabsConnection extends ICustomTabsService.Stub {
         }
         if (referrer == null) referrer = "";
         WebContents webContents = mExternalPrerenderHandler.addPrerender(
-                Profile.getLastUsedProfile(), url, referrer, contentSize.x, contentSize.y);
+                Profile.getLastUsedProfile(), url, referrer, contentSize.x, contentSize.y,
+                shouldPrerenderOnCellularForSession(session));
         if (webContents == null) return false;
         mClientManager.registerPrerenderRequest(uid, url);
         mPrerender = new PrerenderedUrlParams(session, webContents, url, referrer, extras);
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/prerender/ExternalPrerenderHandler.java b/chrome/android/java/src/org/chromium/chrome/browser/prerender/ExternalPrerenderHandler.java
index 0066586..fa94115 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/prerender/ExternalPrerenderHandler.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/prerender/ExternalPrerenderHandler.java
@@ -33,13 +33,15 @@ public class ExternalPrerenderHandler {
      * @param referrer The referrer for the prerender request.
      * @param width The width for the content view (render widget host view) for the prerender.
      * @param height The height for the content view (render widget host view) for the prerender.
+     * @param prerenderOnCellular Whether the prerender should happen if the device has a cellular
+     *                            connection.
      * @return The {@link WebContents} that is linked to this prerender. {@code null} if
      *         unsuccessful.
      */
     public WebContents addPrerender(Profile profile, String url, String referrer, int width,
-            int height) {
+            int height, boolean prerenderOnCellular) {
         WebContents webContents = WebContentsFactory.createWebContents(false, false);
-        if (addPrerender(profile, webContents, url, referrer, width, height)) {
+        if (addPrerender(profile, webContents, url, referrer, width, height, prerenderOnCellular)) {
             return webContents;
         }
         if (webContents != null) webContents.destroy();
@@ -56,12 +58,14 @@ public class ExternalPrerenderHandler {
      * @param referrer The referrer for the prerender request.
      * @param width The width for the content view (render widget host view) for the prerender.
      * @param height The height for the content view (render widget host view) for the prerender.
+     * @param prerenderOnCellular Whether the prerender should happen if the device has a cellular
+     *                            connection.
      * @return Whether the prerender was successful.
      */
     public boolean addPrerender(Profile profile, WebContents webContents, String url,
-            String referrer, int width, int height) {
+            String referrer, int width, int height, boolean prerenderOnCellular) {
         return nativeAddPrerender(mNativeExternalPrerenderHandler, profile, webContents,
-                url, referrer, width, height);
+                url, referrer, width, height, prerenderOnCellular);
     }
 
     /**
@@ -101,7 +105,8 @@ public class ExternalPrerenderHandler {
     private static native long nativeInit();
     private static native boolean nativeAddPrerender(
             long nativeExternalPrerenderHandlerAndroid, Profile profile,
-            WebContents webContents, String url, String referrer, int width, int height);
+            WebContents webContents, String url, String referrer,
+            int width, int height, boolean prerenderOnCellular);
     private static native boolean nativeHasPrerenderedUrl(
             Profile profile, String url, WebContents webContents);
     private static native boolean nativeHasPrerenderedAndFinishedLoadingUrl(
diff --git a/chrome/android/javatests/src/org/chromium/chrome/browser/prerender/ExternalPrerenderRequestTest.java b/chrome/android/javatests/src/org/chromium/chrome/browser/prerender/ExternalPrerenderRequestTest.java
index de527e9..1c3da15 100644
--- a/chrome/android/javatests/src/org/chromium/chrome/browser/prerender/ExternalPrerenderRequestTest.java
+++ b/chrome/android/javatests/src/org/chromium/chrome/browser/prerender/ExternalPrerenderRequestTest.java
@@ -79,7 +79,7 @@ public class ExternalPrerenderRequestTest extends ChromeActivityTestCaseBase<Chr
      * Test adding a prerender and canceling that to add a new one.
      */
     public void testAddPrerenderAndCancel() throws InterruptedException {
-        WebContents webContents = mHandler.addPrerender(mProfile, mGoogleUrl, "", 0, 0);
+        WebContents webContents = mHandler.addPrerender(mProfile, mGoogleUrl, "", 0, 0, false);
         assertTrue(ExternalPrerenderHandler.hasPrerenderedUrl(
                 mProfile, mGoogleUrl, webContents));
 
@@ -88,7 +88,7 @@ public class ExternalPrerenderRequestTest extends ChromeActivityTestCaseBase<Chr
                 mProfile, mGoogleUrl, webContents));
         webContents.destroy();
         Thread.sleep(PRERENDER_DELAY_MS);
-        webContents = mHandler.addPrerender(mProfile, mYoutubeUrl, "", 0, 0);
+        webContents = mHandler.addPrerender(mProfile, mYoutubeUrl, "", 0, 0, false);
         assertTrue(ExternalPrerenderHandler.hasPrerenderedUrl(
                 mProfile, mYoutubeUrl, webContents));
     }
@@ -102,7 +102,7 @@ public class ExternalPrerenderRequestTest extends ChromeActivityTestCaseBase<Chr
      */
     public void testCancelPrerender() {
         mHandler.cancelCurrentPrerender();
-        WebContents webContents = mHandler.addPrerender(mProfile, mGoogleUrl, "", 0, 0);
+        WebContents webContents = mHandler.addPrerender(mProfile, mGoogleUrl, "", 0, 0, false);
         assertTrue(ExternalPrerenderHandler.hasPrerenderedUrl(
                 mProfile, mGoogleUrl, webContents));
     }
@@ -115,11 +115,11 @@ public class ExternalPrerenderRequestTest extends ChromeActivityTestCaseBase<Chr
      * Test adding two prerenders without canceling the first one.
      */
     public void testAddingPrerendersInaRow() throws InterruptedException {
-        WebContents webContents = mHandler.addPrerender(mProfile, mGoogleUrl, "", 0, 0);
+        WebContents webContents = mHandler.addPrerender(mProfile, mGoogleUrl, "", 0, 0, false);
         assertTrue(ExternalPrerenderHandler.hasPrerenderedUrl(
                 mProfile, mGoogleUrl, webContents));
         Thread.sleep(PRERENDER_DELAY_MS);
-        WebContents newWebContents = mHandler.addPrerender(mProfile, mYoutubeUrl, "", 0, 0);
+        WebContents newWebContents = mHandler.addPrerender(mProfile, mYoutubeUrl, "", 0, 0, false);
         assertTrue(ExternalPrerenderHandler.hasPrerenderedUrl(
                 mProfile, mYoutubeUrl, newWebContents));
     }
diff --git a/chrome/browser/prerender/external_prerender_handler_android.cc b/chrome/browser/prerender/external_prerender_handler_android.cc
index 2981f73..22925ef 100644
--- a/chrome/browser/prerender/external_prerender_handler_android.cc
+++ b/chrome/browser/prerender/external_prerender_handler_android.cc
@@ -15,8 +15,8 @@
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_android.h"
 #include "content/public/browser/web_contents.h"
-
 #include "jni/ExternalPrerenderHandler_jni.h"
+#include "net/base/network_change_notifier.h"
 
 using base::android::ConvertJavaStringToUTF16;
 
@@ -57,7 +57,8 @@ bool ExternalPrerenderHandlerAndroid::AddPrerender(
     const JavaParamRef<jstring>& jurl,
     const JavaParamRef<jstring>& jreferrer,
     jint width,
-    jint height) {
+    jint height,
+    jboolean prerender_on_cellular) {
   Profile* profile = ProfileAndroid::FromProfileAndroid(jprofile);
 
   GURL url = GURL(ConvertJavaStringToUTF16(env, jurl));
@@ -77,12 +78,23 @@ bool ExternalPrerenderHandlerAndroid::AddPrerender(
   if (prerender_handle_.get()) {
     prerender_handle_->OnNavigateAway();
   }
-  prerender_handle_.reset(
-      prerender_manager->AddPrerenderFromExternalRequest(
-          url,
-          referrer,
-          web_contents->GetController().GetDefaultSessionStorageNamespace(),
-          gfx::Size(width, height)));
+  if (prerender_on_cellular && net::NetworkChangeNotifier::IsConnectionCellular(
+                   net::NetworkChangeNotifier::GetConnectionType())) {
+    prerender_handle_.reset(
+        prerender_manager->AddPrerenderOnCellularFromExternalRequest(
+            url,
+            referrer,
+            web_contents->GetController().GetDefaultSessionStorageNamespace(),
+            gfx::Size(width, height)));
+  } else {
+    prerender_handle_.reset(
+        prerender_manager->AddPrerenderFromExternalRequest(
+            url,
+            referrer,
+            web_contents->GetController().GetDefaultSessionStorageNamespace(),
+            gfx::Size(width, height)));
+  }
+
   if (!prerender_handle_)
     return false;
   return true;
diff --git a/chrome/browser/prerender/external_prerender_handler_android.h b/chrome/browser/prerender/external_prerender_handler_android.h
index 6aae904..3b1ef82 100644
--- a/chrome/browser/prerender/external_prerender_handler_android.h
+++ b/chrome/browser/prerender/external_prerender_handler_android.h
@@ -35,7 +35,8 @@ class ExternalPrerenderHandlerAndroid {
                     const base::android::JavaParamRef<jstring>& url,
                     const base::android::JavaParamRef<jstring>& referrer,
                     jint width,
-                    jint height);
+                    jint height,
+                    jboolean prerender_on_cellular);
 
   // Cancel the prerender associated with the prerender_handle_
   void CancelCurrentPrerender(
diff --git a/chrome/browser/prerender/prerender_histograms.cc b/chrome/browser/prerender/prerender_histograms.cc
index b7401d0..6e46198 100644
--- a/chrome/browser/prerender/prerender_histograms.cc
+++ b/chrome/browser/prerender/prerender_histograms.cc
@@ -54,6 +54,8 @@ std::string GetHistogramName(Origin origin, bool is_wash,
       return ComposeHistogramName("webnext", name);
     case ORIGIN_GWS_PRERENDER:
       return ComposeHistogramName("gws", name);
+    case ORIGIN_EXTERNAL_REQUEST_FORCED_CELLULAR:
+      return ComposeHistogramName("externalrequestforced", name);
     default:
       NOTREACHED();
       break;
@@ -105,6 +107,8 @@ do { \
     HISTOGRAM; \
   } else if (origin == ORIGIN_LINK_REL_NEXT) { \
     HISTOGRAM; \
+  } else if (origin == ORIGIN_EXTERNAL_REQUEST_FORCED_CELLULAR) { \
+    HISTOGRAM; \
   } else { \
     HISTOGRAM; \
   } \
diff --git a/chrome/browser/prerender/prerender_manager.cc b/chrome/browser/prerender/prerender_manager.cc
index 4bb07b2..1e3e536 100644
--- a/chrome/browser/prerender/prerender_manager.cc
+++ b/chrome/browser/prerender/prerender_manager.cc
@@ -298,7 +298,19 @@ PrerenderHandle* PrerenderManager::AddPrerenderFromExternalRequest(
     const content::Referrer& referrer,
     SessionStorageNamespace* session_storage_namespace,
     const gfx::Size& size) {
-  return AddPrerender(ORIGIN_EXTERNAL_REQUEST, url, referrer, size,
+  return AddPrerender(
+      ORIGIN_EXTERNAL_REQUEST, url, referrer, size, session_storage_namespace);
+}
+
+PrerenderHandle* PrerenderManager::AddPrerenderOnCellularFromExternalRequest(
+    const GURL& url,
+    const content::Referrer& referrer,
+    SessionStorageNamespace* session_storage_namespace,
+    const gfx::Size& size) {
+  return AddPrerender(ORIGIN_EXTERNAL_REQUEST_FORCED_CELLULAR,
+                      url,
+                      referrer,
+                      size,
                       session_storage_namespace);
 }
 
@@ -575,8 +587,10 @@ void PrerenderManager::RecordPerceivedPageLoadTime(
     double fraction_plt_elapsed_at_swap_in,
     const GURL& url) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
-  if (GetPredictionStatus() != NetworkPredictionStatus::ENABLED)
+  if (GetPredictionStatusForOrigin(origin)
+      != NetworkPredictionStatus::ENABLED) {
     return;
+  }
 
   histograms_->RecordPerceivedPageLoadTime(
       origin, perceived_page_load_time, navigation_type, url);
@@ -789,6 +803,12 @@ base::DictionaryValue* PrerenderManager::GetAsValue() const {
   dict_value->Set("active", GetActivePrerendersAsValue());
   dict_value->SetBoolean("enabled",
       GetPredictionStatus() == NetworkPredictionStatus::ENABLED);
+  std::string disabled_note;
+  if (GetPredictionStatus() == NetworkPredictionStatus::DISABLED_ALWAYS)
+    disabled_note = "Disabled by user setting";
+  if (GetPredictionStatus() == NetworkPredictionStatus::DISABLED_DUE_TO_NETWORK)
+    disabled_note = "Disabled on cellular connection by default";
+  dict_value->SetString("disabled_note", disabled_note);
   dict_value->SetBoolean("omnibox_enabled", IsOmniboxEnabled(profile_));
   // If prerender is disabled via a flag this method is not even called.
   std::string enabled_note;
@@ -934,7 +954,8 @@ PrerenderHandle* PrerenderManager::AddPrerender(
   // histogram tracking.
   histograms_->RecordPrerender(origin, url_arg);
 
-  NetworkPredictionStatus prerendering_status = GetPredictionStatus();
+  NetworkPredictionStatus prerendering_status =
+      GetPredictionStatusForOrigin(origin);
   if (prerendering_status != NetworkPredictionStatus::ENABLED) {
     FinalStatus final_status =
         prerendering_status == NetworkPredictionStatus::DISABLED_DUE_TO_NETWORK
@@ -1285,6 +1306,18 @@ NetworkPredictionStatus PrerenderManager::GetPredictionStatus() const {
   return CanPrefetchAndPrerenderUI(profile_->GetPrefs());
 }
 
+NetworkPredictionStatus PrerenderManager::GetPredictionStatusForOrigin(
+    Origin origin) const {
+  DCHECK(CalledOnValidThread());
+  NetworkPredictionStatus prediction_status =
+      CanPrefetchAndPrerenderUI(profile_->GetPrefs());
+  if (prediction_status == NetworkPredictionStatus::DISABLED_DUE_TO_NETWORK
+      && origin == ORIGIN_EXTERNAL_REQUEST_FORCED_CELLULAR) {
+    prediction_status = NetworkPredictionStatus::ENABLED;
+  }
+  return prediction_status;
+}
+
 void PrerenderManager::AddProfileNetworkBytesIfEnabled(int64_t bytes) {
   DCHECK_GE(bytes, 0);
   if (GetPredictionStatus() == NetworkPredictionStatus::ENABLED &&
diff --git a/chrome/browser/prerender/prerender_manager.h b/chrome/browser/prerender/prerender_manager.h
index fdf874e..c33c540 100644
--- a/chrome/browser/prerender/prerender_manager.h
+++ b/chrome/browser/prerender/prerender_manager.h
@@ -134,6 +134,14 @@ class PrerenderManager : public base::SupportsWeakPtr<PrerenderManager>,
       content::SessionStorageNamespace* session_storage_namespace,
       const gfx::Size& size);
 
+  // Adds a prerender from an external request that will prerender even on
+  // cellular networks as long as the user setting for prerendering is ON.
+  PrerenderHandle* AddPrerenderOnCellularFromExternalRequest(
+      const GURL& url,
+      const content::Referrer& referrer,
+      content::SessionStorageNamespace* session_storage_namespace,
+      const gfx::Size& size);
+
   // Adds a prerender for Instant Search |url| if valid. The
   // |session_storage_namespace| matches the namespace of the active tab at the
   // time the prerender is generated. Returns a caller-owned PrerenderHandle* or
@@ -395,6 +403,11 @@ class PrerenderManager : public base::SupportsWeakPtr<PrerenderManager>,
   // disabled.
   chrome_browser_net::NetworkPredictionStatus GetPredictionStatus() const;
 
+  // Returns whether prerendering is currently enabled or the reason why it is
+  // disabled after taking into account the origin of the request.
+  chrome_browser_net::NetworkPredictionStatus GetPredictionStatusForOrigin(
+      Origin origin) const;
+
   // Adds a prerender for |url| from |referrer|. The |origin| specifies how the
   // prerender was added. If |size| is empty, then
   // PrerenderContents::StartPrerendering will instead use a default from
diff --git a/chrome/browser/prerender/prerender_origin.cc b/chrome/browser/prerender/prerender_origin.cc
index c5470ce..3c9b7b6 100644
--- a/chrome/browser/prerender/prerender_origin.cc
+++ b/chrome/browser/prerender/prerender_origin.cc
@@ -26,6 +26,7 @@ const char* kOriginNames[] = {
   "External Request",
   "Instant",
   "Link Rel Next",
+  "External Request Forced Cellular",
   "Max",
 };
 static_assert(arraysize(kOriginNames) == ORIGIN_MAX + 1,
diff --git a/chrome/browser/prerender/prerender_origin.h b/chrome/browser/prerender/prerender_origin.h
index e13ecf4..60e3e0b 100644
--- a/chrome/browser/prerender/prerender_origin.h
+++ b/chrome/browser/prerender/prerender_origin.h
@@ -23,6 +23,7 @@ enum Origin {
   ORIGIN_EXTERNAL_REQUEST = 10,
   ORIGIN_INSTANT = 11,
   ORIGIN_LINK_REL_NEXT = 12,
+  ORIGIN_EXTERNAL_REQUEST_FORCED_CELLULAR = 13,
   ORIGIN_MAX,
 };
 
diff --git a/chrome/browser/prerender/prerender_unittest.cc b/chrome/browser/prerender/prerender_unittest.cc
index c28014b..74ebdcf 100644
--- a/chrome/browser/prerender/prerender_unittest.cc
+++ b/chrome/browser/prerender/prerender_unittest.cc
@@ -31,6 +31,7 @@
 #include "components/prefs/pref_service.h"
 #include "content/public/browser/render_view_host.h"
 #include "content/public/test/test_browser_thread.h"
+#include "net/base/network_change_notifier.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/gfx/geometry/size.h"
 #include "url/gurl.h"
@@ -266,6 +267,13 @@ class RestorePrerenderMode {
   PrerenderManager::PrerenderManagerMode prev_mode_;
 };
 
+class MockNetworkChangeNotifier4G : public net::NetworkChangeNotifier {
+ public:
+  ConnectionType GetCurrentConnectionType() const override {
+    return NetworkChangeNotifier::CONNECTION_4G;
+  }
+};
+
 DummyPrerenderContents::DummyPrerenderContents(
     UnitTestPrerenderManager* test_prerender_manager,
     const GURL& url,
@@ -379,6 +387,12 @@ class PrerenderTest : public testing::Test {
         chrome_browser_net::NETWORK_PREDICTION_NEVER);
   }
 
+  void EnablePrerender() {
+    profile_.GetPrefs()->SetInteger(
+        prefs::kNetworkPredictionOptions,
+        chrome_browser_net::NETWORK_PREDICTION_ALWAYS);
+  }
+
  private:
   // Needed to pass PrerenderManager's DCHECKs.
   base::MessageLoop message_loop_;
@@ -1046,6 +1060,58 @@ TEST_F(PrerenderTest, LinkRelNotAllowedWhenDisabled) {
       GURL("http://www.example.com")));
 }
 
+TEST_F(PrerenderTest, PrerenderNotAllowedOnCellular) {
+  EnablePrerender();
+  scoped_ptr<net::NetworkChangeNotifier> mock(
+      new MockNetworkChangeNotifier4G);
+  EXPECT_TRUE(net::NetworkChangeNotifier::IsConnectionCellular(
+      net::NetworkChangeNotifier::GetConnectionType()));
+  EXPECT_FALSE(AddSimplePrerender(GURL("http://www.example.com")));
+}
+
+TEST_F(PrerenderTest, PrerenderNotAllowedOnCellularWithExternalOrigin) {
+  EnablePrerender();
+  scoped_ptr<net::NetworkChangeNotifier> mock(
+      new MockNetworkChangeNotifier4G);
+  EXPECT_TRUE(net::NetworkChangeNotifier::IsConnectionCellular(
+      net::NetworkChangeNotifier::GetConnectionType()));
+  GURL url("http://www.google.com/");
+  DummyPrerenderContents* prerender_contents =
+      prerender_manager()->CreateNextPrerenderContents(
+          url,
+          ORIGIN_EXTERNAL_REQUEST,
+          FINAL_STATUS_MANAGER_SHUTDOWN);
+  scoped_ptr<PrerenderHandle> prerender_handle(
+      prerender_manager()->AddPrerenderFromExternalRequest(
+          url, content::Referrer(), nullptr, kSize));
+  EXPECT_FALSE(prerender_handle);
+  EXPECT_FALSE(prerender_contents->prerendering_has_started());
+}
+
+TEST_F(PrerenderTest,PrerenderAllowedOnCellularWithForcedOrigin) {
+  EnablePrerender();
+  scoped_ptr<net::NetworkChangeNotifier> mock(
+      new MockNetworkChangeNotifier4G);
+  EXPECT_TRUE(net::NetworkChangeNotifier::IsConnectionCellular(
+      net::NetworkChangeNotifier::GetConnectionType()));
+  GURL url("http://www.google.com/");
+  DummyPrerenderContents* prerender_contents =
+      prerender_manager()->CreateNextPrerenderContents(
+          url,
+          ORIGIN_EXTERNAL_REQUEST_FORCED_CELLULAR,
+          FINAL_STATUS_USED);
+  scoped_ptr<PrerenderHandle> prerender_handle(
+      prerender_manager()->AddPrerenderOnCellularFromExternalRequest(
+          url, content::Referrer(), nullptr, kSize));
+  EXPECT_TRUE(prerender_handle);
+  EXPECT_TRUE(prerender_handle->IsPrerendering());
+  EXPECT_TRUE(prerender_contents->prerendering_has_started());
+  EXPECT_EQ(prerender_contents, prerender_handle->contents());
+  EXPECT_EQ(ORIGIN_EXTERNAL_REQUEST_FORCED_CELLULAR,
+    prerender_handle->contents()->origin());
+  ASSERT_EQ(prerender_contents, prerender_manager()->FindAndUseEntry(url));
+}
+
 TEST_F(PrerenderTest, LinkManagerCancel) {
   EXPECT_TRUE(IsEmptyPrerenderLinkManager());
   GURL url("http://www.myexample.com");
diff --git a/chrome/test/android/javatests/src/org/chromium/chrome/test/util/PrerenderTestHelper.java b/chrome/test/android/javatests/src/org/chromium/chrome/test/util/PrerenderTestHelper.java
index 2a7a8ecc..0c67fd1 100644
--- a/chrome/test/android/javatests/src/org/chromium/chrome/test/util/PrerenderTestHelper.java
+++ b/chrome/test/android/javatests/src/org/chromium/chrome/test/util/PrerenderTestHelper.java
@@ -97,7 +97,8 @@ public class PrerenderTestHelper {
                                 currentTab.getContentViewCore().getRenderCoordinates()
                                         .getContentWidthPixInt(),
                                 currentTab.getContentViewCore().getRenderCoordinates()
-                                        .getContentHeightPixInt());
+                                        .getContentHeightPixInt(),
+                                false);
                         Assert.assertTrue("Failed to prerender test url: " + testUrl, didPrerender);
                         return prerenderHandler;
                     }
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 37aad5a..deb3b16 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -87739,6 +87739,8 @@ To add a new entry, add it with any value and run test to compute valid value.
   </suffix>
   <suffix name="gws" label="GWS triggered prerender."/>
   <suffix name="externalrequest" label="Externally triggered prerender."/>
+  <suffix name="externalrequestforced"
+      label="Forced prerender regardless of network."/>
   <suffix name="Instant" label="Instant search prerender."/>
   <suffix name="localpredictor" label="Local predictor triggered prerender.">
     <obsolete>