Make WebView respond to device scale change

android_webview/java/src/org/chromium/android_webview/AwContents.java

Index: android_webview/java/src/org/chromium/android_webview/AwContents.java
diff --git a/android_webview/java/src/org/chromium/android_webview/AwContents.java b/android_webview/java/src/org/chromium/android_webview/AwContents.java
index a3dbd95e3576653464aabdc50a83f32b418d5df6..d9349d576e73d741d415f3282cd4f51f6be2fcad 100644
--- a/android_webview/java/src/org/chromium/android_webview/AwContents.java
+++ b/android_webview/java/src/org/chromium/android_webview/AwContents.java
@@ -300,7 +300,7 @@ public class AwContents implements SmartClipProvider,
     private Bitmap mFavicon;
     private boolean mHasRequestedVisitedHistoryFromClient;
     // TODO(boliu): This should be in a global context, not per webview.
-    private final double mDIPScale;
+    private double mDIPScale;
     // Whether this WebView is a popup.
     private boolean mIsPopupWindow = false;
 
@@ -712,6 +712,16 @@ public class AwContents implements SmartClipProvider,
         public void onConfigurationChanged(Configuration configuration) {
             setLocale(LocaleUtils.getLocale(configuration.locale));
             mSettings.updateAcceptLanguages();
+
+            DeviceDisplayInfo displayInfo = DeviceDisplayInfo.create(mContext);
+            // Update all display related parameters.
+            displayInfo.updateNativeSharedDisplayInfo();
+
+            final double newDIPScale = displayInfo.getDIPScale();
+            if (newDIPScale != mDIPScale) {
+                mContentViewCore.setDeviceScaleFactor((float) newDIPScale);
+                setDIPScale(newDIPScale);
+            }
         }
     };
 
@@ -771,9 +781,7 @@ public class AwContents implements SmartClipProvider,
         mContentViewClient = new AwContentViewClient(contentsClient, settings, this, mContext);
         mLayoutSizer = dependencyFactory.createLayoutSizer();
         mSettings = settings;
-        mDIPScale = DeviceDisplayInfo.create(mContext).getDIPScale();
         mLayoutSizer.setDelegate(new AwLayoutSizerDelegate());
-        mLayoutSizer.setDIPScale(mDIPScale);
         mWebContentsDelegate = new AwWebContentsDelegateAdapter(
                 this, contentsClient, mContentViewClient, mContext, mContainerView);
         mContentsClientBridge = new AwContentsClientBridge(mContext, contentsClient,
@@ -804,7 +812,6 @@ public class AwContents implements SmartClipProvider,
         mDefaultVideoPosterRequestHandler = new DefaultVideoPosterRequestHandler(mContentsClient);
         mSettings.setDefaultVideoPosterURL(
                 mDefaultVideoPosterRequestHandler.getDefaultVideoPosterURL());
-        mSettings.setDIPScale(mDIPScale);
         mScrollOffsetManager =
                 dependencyFactory.createScrollOffsetManager(new AwScrollOffsetManagerDelegate());
         mScrollAccessibilityHelper = new ScrollAccessibilityHelper(mContainerView);
@@ -829,6 +836,13 @@ public class AwContents implements SmartClipProvider,
         contentViewCore.setZoomControlsDelegate(zoomControlsDelegate);
     }
 
+    private void setDIPScale(double dipScale) {
+        mDIPScale = dipScale;
+        nativeSetDipScale(mNativeAwContents, (float) mDIPScale);
+        mSettings.setDIPScale(mDIPScale);
+        mLayoutSizer.setDIPScale(mDIPScale);
+    }
+
     boolean isFullScreen() {
         return mFullScreenTransitionsState.isFullScreen();
     }
@@ -1061,7 +1075,10 @@ public class AwContents implements SmartClipProvider,
         mNavigationController = mWebContents.getNavigationController();
         installWebContentsObserver();
         mSettings.setWebContents(webContents);
-        nativeSetDipScale(mNativeAwContents, (float) mDIPScale);
+
+        // ContentViewCore requests and stores the device scale factor.
+        setDIPScale(mContentViewCore.getDeviceScaleFactor());
+
         updateContentViewCoreVisibility();
 
         // The native side object has been bound to this java instance, so now is the time to