Disable Reader Mode when requesting desktop site

If requesting a desktop site on mobile, Reader Mode will no longer
trigger unless its heuristic is set to ALWAYS_TRUE.

BUG=647086

Review-Url: https://codereview.chromium.org/2342873005
Cr-Commit-Position: refs/heads/master@{#419562}

chrome/android/java/src/org/chromium/chrome/browser/dom_distiller/DomDistillerTabUtils.java

@@ -59,9 +59,20 @@ public class DomDistillerTabUtils {
         return nativeIsDistillerHeuristicsEnabled();
     }
 
+    /**
+     * Check if the distiller is reporting every page as distillable.
+     *
+     * @return True if heuristic is ALWAYS_TRUE.
+     */
+    public static boolean isHeuristicAlwaysTrue() {
+        return nativeIsHeuristicAlwaysTrue();
+    }
+
+
     private static native void nativeDistillCurrentPageAndView(WebContents webContents);
     private static native void nativeDistillAndView(
             WebContents sourceWebContents, WebContents destinationWebContents);
     private static native String nativeGetFormattedUrlFromOriginalDistillerUrl(String url);
     private static native boolean nativeIsDistillerHeuristicsEnabled();
+    private static native boolean nativeIsHeuristicAlwaysTrue();
 }

chrome/android/java/src/org/chromium/chrome/browser/dom_distiller/ReaderModeManager.java

@@ -92,6 +92,9 @@ public class ReaderModeManager extends TabModelSelectorTabObserver
     // InfoBar tracking.
     private boolean mIsInfoBarContainerShown;
 
+    // If Reader Mode is detecting all pages as distillable.
+    private boolean mIsReaderHeuristicAlwaysTrue;
+
 
     public ReaderModeManager(TabModelSelector selector, ChromeActivity activity) {
         super(selector);
@@ -99,6 +102,15 @@ public class ReaderModeManager extends TabModelSelectorTabObserver
         mTabModelSelector = selector;
         mChromeActivity = activity;
         mTabStatusMap = new HashMap<>();
+        mIsReaderHeuristicAlwaysTrue = isDistillerHeuristicAlwaysTrue();
+    }
+
+    /**
+     * This function wraps a method that calls native code and is overridden by tests.
+     * @return True if the heuristic is ALWAYS_TRUE.
+     */
+    protected boolean isDistillerHeuristicAlwaysTrue() {
+        return DomDistillerTabUtils.isHeuristicAlwaysTrue();
     }
 
     /**
@@ -508,7 +520,14 @@ public class ReaderModeManager extends TabModelSelectorTabObserver
         int currentTabId = mTabModelSelector.getCurrentTabId();
         if (currentTabId == Tab.INVALID_TAB_ID) return;
 
+        // Test if the user is requesting the desktop site. Ignore this if distiller is set to
+        // ALWAYS_TRUE.
+        boolean usingRequestDesktopSite = getBasePageWebContents() != null
+                && getBasePageWebContents().getNavigationController().getUseDesktopUserAgent()
+                && !mIsReaderHeuristicAlwaysTrue;
+
         if (mReaderModePanel == null || !mTabStatusMap.containsKey(currentTabId)
+                || usingRequestDesktopSite
                 || mTabStatusMap.get(currentTabId).getStatus() != POSSIBLE
                 || mTabStatusMap.get(currentTabId).isDismissed()
                 || mIsInfoBarContainerShown

chrome/android/javatests/src/org/chromium/chrome/browser/dom_distiller/ReaderModeManagerTest.java

@@ -79,6 +79,11 @@ public class ReaderModeManagerTest extends InstrumentationTestCase {
             return null;
         }
 
+        @Override
+        protected boolean isDistillerHeuristicAlwaysTrue() {
+            return true;
+        }
+
         @Override
         protected void recordPanelVisibilityForNavigation(boolean visible) {
             mRecordedCount++;

chrome/browser/dom_distiller/tab_utils_android.cc

@@ -68,6 +68,13 @@ jboolean IsDistillerHeuristicsEnabled(JNIEnv* env,
       != dom_distiller::DistillerHeuristicsType::NONE;
 }
 
+// Returns true if distiller is reporting every page as distillable.
+jboolean IsHeuristicAlwaysTrue(JNIEnv* env,
+                               const JavaParamRef<jclass>& clazz) {
+  return dom_distiller::GetDistillerHeuristicsType()
+      == dom_distiller::DistillerHeuristicsType::ALWAYS_TRUE;
+}
+
 }  // namespace android
 
 bool RegisterDomDistillerTabUtils(JNIEnv* env) {