Add observers for DIP 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 0a5293ba55910c06f9f875e7fbe0115e5489ad2b..03cb36b9f8ffd4012c249b9738ae46e8a4d5c4b1 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
@@ -86,6 +86,7 @@ import org.chromium.ui.base.DeviceFormFactor;
 import org.chromium.ui.base.ViewAndroidDelegate;
 import org.chromium.ui.base.WindowAndroid;
 import org.chromium.ui.base.ime.TextInputType;
+import org.chromium.ui.display.DisplayAndroid;
 import org.chromium.ui.display.DisplayAndroid.DisplayAndroidObserver;
 import org.chromium.ui.touch_selection.SelectionEventType;
 
@@ -659,7 +660,7 @@ public class ContentViewCore implements AccessibilityStateChangeListener, Displa
         setContainerViewInternals(internalDispatcher);
 
         mRenderCoordinates.reset();
-        mRenderCoordinates.updateDeviceScaleFactorFromWindow(windowAndroid);
+        updateDeviceScaleFactorFromWindow(windowAndroid);
 
         initPopupZoomer(mContext);
         mImeAdapter = createImeAdapter();
@@ -694,9 +695,10 @@ public class ContentViewCore implements AccessibilityStateChangeListener, Displa
         if (!mAttachedToWindow) return;
         WindowAndroid windowAndroid = getWindowAndroid();
         if (windowAndroid != null) {
-            mRenderCoordinates.updateDeviceScaleFactorFromWindow(windowAndroid);
-            windowAndroid.getDisplay().addObserver(this);
-            onRotationChanged(windowAndroid.getDisplay().getRotation());
+            DisplayAndroid display = windowAndroid.getDisplay();
+            display.addObserver(this);
+            onRotationChanged(display.getRotation());
+            onDIPScaleChanged(display.getDIPScale());
         }
     }
 
@@ -3234,6 +3236,7 @@ public class ContentViewCore implements AccessibilityStateChangeListener, Displa
         updateGestureStateListener(GestureEventType.FLING_END);
     }
 
+    // DisplayAndroidObserver method.
     @Override
     public void onRotationChanged(int rotation) {
         // ActionMode#invalidate() won't be able to re-layout the floating
@@ -3266,6 +3269,26 @@ public class ContentViewCore implements AccessibilityStateChangeListener, Displa
         sendOrientationChangeEvent(rotationDegrees);
     }
 
+    // DisplayAndroidObserver method.
+    @Override
+    public void onDIPScaleChanged(float dipScale) {
+        Context displayContext =
+                getWindowAndroid() == null ? null : getWindowAndroid().getContext().get();

[boliu, 2016/10/18 00:26:25]

should this be an assert?

[Tima Vaisburd, 2016/10/19 01:15:54]

This method might be called directly by DisplayAndroid and thus not protected by
condition windowAndroid != null. I added this condition (early return) instead
of assert.

+        mRenderCoordinates.setDeviceScaleFactor(dipScale, displayContext);
+
+        if (mNativeContentViewCore == 0) return;
+        nativeSetDIPScale(mNativeContentViewCore, dipScale, true); // force layout

[boliu, 2016/10/18 00:26:25]

format it like (..., true /* force layout */);

[Tima Vaisburd, 2016/10/19 01:15:54]

Done.

+    }
+
+    private void updateDeviceScaleFactorFromWindow(WindowAndroid window) {

[boliu, 2016/10/18 00:26:25]

there is only one caller, just inline it?

[Tima Vaisburd, 2016/10/19 01:15:54]

Done.

+        float dipScale = window.getDisplay().getDIPScale();
+        Context displayContext = window.getContext().get();
+        mRenderCoordinates.setDeviceScaleFactor(dipScale, displayContext);
+
+        if (mNativeContentViewCore == 0) return;
+        nativeSetDIPScale(mNativeContentViewCore, dipScale, false); // do not force layout

[boliu, 2016/10/18 00:26:25]

ditto about formatting

[Tima Vaisburd, 2016/10/19 01:15:54]

Done.

+    }
+
     /**
      * Set whether the ContentViewCore requires the WebContents to be fullscreen in order to lock
      * the screen orientation.
@@ -3330,6 +3353,9 @@ public class ContentViewCore implements AccessibilityStateChangeListener, Displa
 
     private native void nativeSetFocus(long nativeContentViewCoreImpl, boolean focused);
 
+    private native void nativeSetDIPScale(
+            long nativeContentViewCoreImpl, float dipScale, boolean forceLayout);
+
     private native void nativeSendOrientationChangeEvent(
             long nativeContentViewCoreImpl, int orientation);