Make WebView respond to device scale change

content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java

Index: content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
diff --git a/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java b/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
index f7f3ccedb74ef11394aca7df48d17a9b69874e5d..f6fe34efc886356b615bb1ab660f36d28edbd970 100644
--- a/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
+++ b/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
@@ -955,6 +955,15 @@ public class ContentViewCore implements AccessibilityStateChangeListener, Screen
     }
 
     /**
+     * Sets the device scale factor (maps DIP pixels to physical pixels).
+     */
+    public void setDeviceScaleFactor(float value) {
+        mRenderCoordinates.setDeviceScaleFactor(value);
+        if (mNativeContentViewCore == 0) return;
+        nativeSetDeviceScaleFactor(mNativeContentViewCore, value);
+    }
+
+    /**
      * @return Current page scale factor (maps CSS pixels to DIP pixels).
      */
     @VisibleForTesting
@@ -1471,6 +1480,28 @@ public class ContentViewCore implements AccessibilityStateChangeListener, Screen
         }
     }
 
+    /**
+      * Called when the underlying surface size and the viewport size are changed
+      * simultaneously. This may happen in WebView.
+      */
+    public void onPhysicalAndViewportSizeChanged(int wPix, int hPix) {
+        if (mPhysicalBackingWidthPix == wPix && mPhysicalBackingHeightPix == hPix
+                && getViewportWidthPix() == wPix && getViewportHeightPix() == hPix) {
+            return;
+        }
+
+        mPhysicalBackingWidthPix = wPix;
+        mPhysicalBackingHeightPix = hPix;
+        mViewportWidthPix = wPix;
+        mViewportHeightPix = hPix;
+
+        if (mNativeContentViewCore != 0) {
+            nativeWasResized(mNativeContentViewCore);
+        }
+
+        updateAfterSizeChanged();
+    }
+
     private void updateAfterSizeChanged() {
         mPopupZoomer.hide(false);
 
@@ -3321,6 +3352,8 @@ public class ContentViewCore implements AccessibilityStateChangeListener, Screen
 
     private native void nativeSetFocus(long nativeContentViewCoreImpl, boolean focused);
 
+    private native void nativeSetDeviceScaleFactor(long nativeContentViewCoreImpl, float value);
+
     private native void nativeSendOrientationChangeEvent(
             long nativeContentViewCoreImpl, int orientation);