OffscreenPreRaster and its plumbings

If OffscreenPreRaster is enabled, the viewport rect for tile priority
and the tile memory limit calculation will be based on the size of the
webview, instead of the size of visible area of the webview.

Design doc here
https://docs.google.com/document/d/1xOMjvbEIS3dMzpWXWrsl7qV8QOgGEIZL1QxgnfOXmq4/

BUG=460638

Review URL: https://codereview.chromium.org/944053004

Cr-Commit-Position: refs/heads/master@{#318126}

4 files changed, 17 insertions, 0 deletions

diff --git a/android_webview/native/aw_contents.cc b/android_webview/native/aw_contents.cc
index c3c3110..0b034ed 100644
--- a/android_webview/native/aw_contents.cc
+++ b/android_webview/native/aw_contents.cc
@@ -400,6 +400,11 @@ bool AwContents::OnReceivedHttpAuthRequest(const JavaRef<jobject>& handler,
   return true;
 }
 
+void AwContents::SetOffscreenPreRaster(bool enabled) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  browser_view_renderer_.SetOffscreenPreRaster(enabled);
+}
+
 void AwContents::AddVisitedLinks(JNIEnv* env,
                                    jobject obj,
                                    jobjectArray jvisited_links) {
diff --git a/android_webview/native/aw_contents.h b/android_webview/native/aw_contents.h
index ce3c911..edb60ef 100644
--- a/android_webview/native/aw_contents.h
+++ b/android_webview/native/aw_contents.h
@@ -81,6 +81,8 @@ class AwContents : public FindHelper::Listener,
                                  const std::string& host,
                                  const std::string& realm);
 
+  void SetOffscreenPreRaster(bool enabled);
+
   // Methods called from Java.
   void SetJavaPeers(JNIEnv* env,
                     jobject obj,
diff --git a/android_webview/native/aw_settings.cc b/android_webview/native/aw_settings.cc
index 6589e96..91c5064 100644
--- a/android_webview/native/aw_settings.cc
+++ b/android_webview/native/aw_settings.cc
@@ -131,6 +131,7 @@ void AwSettings::UpdateEverythingLocked(JNIEnv* env, jobject obj) {
   ResetScrollAndScaleState(env, obj);
   UpdateFormDataPreferencesLocked(env, obj);
   UpdateRendererPreferencesLocked(env, obj);
+  UpdateOffscreenPreRasterLocked(env, obj);
 }
 
 void AwSettings::UpdateUserAgentLocked(JNIEnv* env, jobject obj) {
@@ -209,6 +210,14 @@ void AwSettings::UpdateRendererPreferencesLocked(JNIEnv* env, jobject obj) {
     host->SyncRendererPrefs();
 }
 
+void AwSettings::UpdateOffscreenPreRasterLocked(JNIEnv* env, jobject obj) {
+  AwContents* contents = AwContents::FromWebContents(web_contents());
+  if (contents) {
+    contents->SetOffscreenPreRaster(
+        Java_AwSettings_getOffscreenPreRasterLocked(env, obj));
+  }
+}
+
 void AwSettings::RenderViewCreated(content::RenderViewHost* render_view_host) {
   // A single WebContents can normally have 0 to many RenderViewHost instances
   // associated with it.
diff --git a/android_webview/native/aw_settings.h b/android_webview/native/aw_settings.h
index 581a6cd..56b09ad 100644
--- a/android_webview/native/aw_settings.h
+++ b/android_webview/native/aw_settings.h
@@ -38,6 +38,7 @@ class AwSettings : public content::WebContentsObserver {
   void UpdateWebkitPreferencesLocked(JNIEnv* env, jobject obj);
   void UpdateFormDataPreferencesLocked(JNIEnv* env, jobject obj);
   void UpdateRendererPreferencesLocked(JNIEnv* env, jobject obj);
+  void UpdateOffscreenPreRasterLocked(JNIEnv* env, jobject obj);
 
   void PopulateWebPreferences(content::WebPreferences* web_prefs);