Add observers for DIP scale change.

content/browser/android/content_view_core_impl.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/android/content_view_core_impl.h"
 
 #include <stddef.h>
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_array.h"
@@ skipping 197 matching lines @@
     const JavaRef<jobject>& obj,
     WebContents* web_contents,
     const JavaRef<jobject>& view_android_delegate,
     ui::WindowAndroid* window_android,
     const JavaRef<jobject>& java_bridge_retained_object_set)
     : WebContentsObserver(web_contents),
       java_ref_(env, obj),
       view_(view_android_delegate),
       web_contents_(static_cast<WebContentsImpl*>(web_contents)),
       page_scale_(1),
-      dpi_scale_(ui::GetScaleFactorForNativeView(&view_)),
+      dpi_scale_(1),

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

why is this change needed?

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

It is actually not needed, but I wanted to make it consistent with the Java side
and make it clear that DIP scale will be explicitly set.
I reverted this change.
I also changed the initial DIP scale in RenderCoordinates.java from 0 to 1.

       device_orientation_(0),
       accessibility_enabled_(false) {
   CHECK(web_contents) <<
       "A ContentViewCoreImpl should be created with a valid WebContents.";
   DCHECK(window_android);
   DCHECK(!view_android_delegate.is_null());
   window_android->AddChild(&view_);
   view_.SetLayer(cc::Layer::Create());
   gfx::Size physical_size(
       Java_ContentViewCore_getPhysicalBackingWidthPix(env, obj),
@@ skipping 567 matching lines @@
 }
 
 float ContentViewCoreImpl::GetTopControlsHeightDip() const {
   return GetTopControlsHeightPix() / dpi_scale();
 }
 
 float ContentViewCoreImpl::GetBottomControlsHeightDip() const {
   return GetBottomControlsHeightPix() / dpi_scale();
 }
 
+void ContentViewCoreImpl::ForceLayout() {

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

just call this "WasResized"?

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

WasResized() already existed, now it sets the physical size and then calls this
ForceLayout(). See below.

+  RenderWidgetHostViewAndroid* view = GetRenderWidgetHostViewAndroid();
+  if (view) {
+    // |SendScreenRects()| indirectly calls GetViewSize() that asks Java layer.
+    web_contents_->SendScreenRects();
+    view->WasResized();
+  }
+}
+
 void ContentViewCoreImpl::MoveRangeSelectionExtent(const gfx::PointF& extent) {
   if (!web_contents_)
     return;
 
   web_contents_->MoveRangeSelectionExtent(gfx::ToRoundedPoint(extent));
 }
 
 void ContentViewCoreImpl::SelectBetweenCoordinates(const gfx::PointF& base,
                                                    const gfx::PointF& extent) {
   if (!web_contents_)
@@ skipping 45 matching lines @@
 WebContents* ContentViewCoreImpl::GetWebContents() const {
   return web_contents_;
 }
 
 void ContentViewCoreImpl::SetFocus(JNIEnv* env,
                                    const JavaParamRef<jobject>& obj,
                                    jboolean focused) {
   SetFocusInternal(focused);
 }
 
+void ContentViewCoreImpl::SetDIPScale(JNIEnv* env,
+                                      const JavaParamRef<jobject>& obj,
+                                      jfloat dipScale,
+                                      jboolean forceLayout) {
+  dpi_scale_ = dipScale;
+  if (forceLayout)
+    ForceLayout();
+}
+
 void ContentViewCoreImpl::SetFocusInternal(bool focused) {
   if (!GetRenderWidgetHostViewAndroid())
     return;
 
   if (focused)
     GetRenderWidgetHostViewAndroid()->Focus();
   else
     GetRenderWidgetHostViewAndroid()->Blur();
 }
 
@@ skipping 348 matching lines @@
 void ContentViewCoreImpl::RemoveJavascriptInterface(
     JNIEnv* env,
     const JavaParamRef<jobject>& /* obj */,
     const JavaParamRef<jstring>& name) {
   java_bridge_dispatcher_host_->RemoveNamedObject(
       ConvertJavaStringToUTF8(env, name));
 }
 
 void ContentViewCoreImpl::WasResized(JNIEnv* env,
                                      const JavaParamRef<jobject>& obj) {
-  RenderWidgetHostViewAndroid* view = GetRenderWidgetHostViewAndroid();
   gfx::Size physical_size(
       Java_ContentViewCore_getPhysicalBackingWidthPix(env, obj),
       Java_ContentViewCore_getPhysicalBackingHeightPix(env, obj));
   view_.GetLayer()->SetBounds(physical_size);
 
-  if (view) {
-    web_contents_->SendScreenRects();
-    view->WasResized();
-  }
+  ForceLayout();
 }
 
 long ContentViewCoreImpl::GetNativeImeAdapter(
     JNIEnv* env,
     const JavaParamRef<jobject>& obj) {
   RenderWidgetHostViewAndroid* rwhva = GetRenderWidgetHostViewAndroid();
   if (!rwhva)
     return 0;
   return rwhva->GetNativeImeAdapter();
 }
@@ skipping 318 matching lines @@
     return ScopedJavaLocalRef<jobject>();
 
   return view->GetJavaObject();
 }
 
 bool RegisterContentViewCore(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }
 
 }  // namespace content