Android: Fix wrong tap postion in a11y mode

https://crrev.com/c/517683 introduced a bug in accessibility mode
when page scale factor is not 1. Before the patch, the hover event
coordinate is converted to CSS (https://goo.gl/ER8wu5) but after
the patch the unit was DIP by mistake. (https://goo.gl/ER8wu5).
This CL fixes it by applying the page scale factor to set the unit
right to CSS.

Bug: 840609
Change-Id: Iaa17882e2ffb2d5637e59df1ebe7cf677f4a76a3
Reviewed-on: https://chromium-review.googlesource.com/1055067
Commit-Queue: Jinsuk Kim <jinsukkim@chromium.org>
Reviewed-by: Bo <boliu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#558165}

content/browser/accessibility/web_contents_accessibility_android.cc

@@ -551,6 +551,7 @@ bool WebContentsAccessibilityAndroid::OnHoverEvent(
       root_manager_) {
     gfx::PointF point =
         IsUseZoomForDSFEnabled() ? event.GetPointPix() : event.GetPoint();
+    point.Scale(1 / page_scale_);
     root_manager_->HitTest(gfx::ToFlooredPoint(point));
   }
   return true;
@@ -1196,7 +1197,8 @@ BrowserAccessibilityAndroid* WebContentsAccessibilityAndroid::GetAXFromUniqueID(
       BrowserAccessibilityAndroid::GetFromUniqueId(unique_id));
 }
 
-void WebContentsAccessibilityAndroid::UpdateFrameInfo() {
+void WebContentsAccessibilityAndroid::UpdateFrameInfo(float page_scale) {
+  page_scale_ = page_scale;
   if (frame_info_initialized_)
     return;
 

content/browser/accessibility/web_contents_accessibility_android.h

@@ -213,7 +213,7 @@ class CONTENT_EXPORT WebContentsAccessibilityAndroid
       jint start,
       jint len);
 
-  void UpdateFrameInfo();
+  void UpdateFrameInfo(float page_scale);
 
   void set_root_manager(BrowserAccessibilityManagerAndroid* manager) {
     root_manager_ = manager;
@@ -253,6 +253,8 @@ class CONTENT_EXPORT WebContentsAccessibilityAndroid
 
   bool frame_info_initialized_;
 
+  float page_scale_ = 1.f;
+
   BrowserAccessibilityManagerAndroid* root_manager_;
 
   // Manages the connection between web contents and the RenderFrameHost that

content/browser/renderer_host/render_widget_host_view_android.cc

@@ -1233,7 +1233,7 @@ void RenderWidgetHostViewAndroid::OnFrameMetadataUpdated(
 
   auto* wcax = GetWebContentsAccessibilityAndroid();
   if (wcax)
-    wcax->UpdateFrameInfo();
+    wcax->UpdateFrameInfo(frame_metadata.page_scale_factor);
 
   if (!gesture_listener_manager_)
     return;