Fix white flash in navigation initial

The page show white color in navigation initial. For dark mode, this excepted a dark color.
If developer don't set WebView background color, just show a black background in dark mode.

Bug: 1098235
Change-Id: I9b221d0a899d228c71f6ce3b9a46c9dda45c4536
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2256921
Commit-Queue: Richard Coles <torne@chromium.org>
Reviewed-by: Richard Coles <torne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#788780}

AUTHORS

@@ -1182,4 +1182,5 @@ Venture 3 Systems LLC <*@venture3systems.com>
 Vewd Software AS <*@vewd.com>
 Vivaldi Technologies AS <*@vivaldi.com>
 Yandex LLC <*@yandex-team.ru>
+XiangYang <yangxiang12@huawei.com>
 # END organizations section.

android_webview/browser/aw_settings.cc

@@ -78,6 +78,7 @@ AwSettings::AwSettings(JNIEnv* env,
       javascript_can_open_windows_automatically_(false),
       allow_third_party_cookies_(false),
       allow_file_access_(false),
+      is_dark_mode_(false),
       aw_settings_(env, obj) {
   web_contents->SetUserData(kAwSettingsUserDataKey,
                             std::make_unique<AwSettingsUserData>(this));
@@ -515,24 +516,23 @@ void AwSettings::PopulateWebPreferencesLocked(JNIEnv* env,
   web_prefs->allow_mixed_content_upgrades =
       Java_AwSettings_getAllowMixedContentAutoupgradesLocked(env, obj);
 
-  bool is_dark_mode;
   switch (Java_AwSettings_getForceDarkModeLocked(env, obj)) {
     case ForceDarkMode::FORCE_DARK_OFF:
-      is_dark_mode = false;
+      is_dark_mode_ = false;
       break;
     case ForceDarkMode::FORCE_DARK_ON:
-      is_dark_mode = true;
+      is_dark_mode_ = true;
       break;
     case ForceDarkMode::FORCE_DARK_AUTO: {
       AwContents* contents = AwContents::FromWebContents(web_contents());
-      is_dark_mode = contents && contents->GetViewTreeForceDarkState();
+      is_dark_mode_ = contents && contents->GetViewTreeForceDarkState();
       break;
     }
   }
-  web_prefs->preferred_color_scheme = is_dark_mode
+  web_prefs->preferred_color_scheme = is_dark_mode_
                                           ? blink::PreferredColorScheme::kDark
                                           : blink::PreferredColorScheme::kLight;
-  if (is_dark_mode) {
+  if (is_dark_mode_) {
     switch (Java_AwSettings_getForceDarkBehaviorLocked(env, obj)) {
       case ForceDarkBehavior::FORCE_DARK_ONLY: {
         web_prefs->preferred_color_scheme = blink::PreferredColorScheme::kLight;
@@ -562,6 +562,11 @@ void AwSettings::PopulateWebPreferencesLocked(JNIEnv* env,
   }
 }
 
+bool AwSettings::IsDarkMode(JNIEnv* env,
+                                 const JavaParamRef<jobject>& obj) {
+  return is_dark_mode_;
+}
+
 bool AwSettings::GetAllowFileAccess() {
   return allow_file_access_;
 }

android_webview/browser/aw_settings.h

@@ -85,6 +85,8 @@ class AwSettings : public content::WebContentsObserver {
 
   void PopulateWebPreferences(content::WebPreferences* web_prefs);
   bool GetAllowFileAccess();
+  bool IsDarkMode(JNIEnv* env,
+                       const base::android::JavaParamRef<jobject>& obj);
 
  private:
   AwRenderViewHostExt* GetAwRenderViewHostExt();
@@ -99,6 +101,7 @@ class AwSettings : public content::WebContentsObserver {
   bool javascript_can_open_windows_automatically_;
   bool allow_third_party_cookies_;
   bool allow_file_access_;
+  bool is_dark_mode_;
 
   JavaObjectWeakGlobalRef aw_settings_;
 };

android_webview/java/src/org/chromium/android_webview/AwContents.java

@@ -424,6 +424,9 @@ public abstract static class VisualStateCallback {
     // The base background color, i.e. not accounting for any CSS body from the current page.
     private int mBaseBackgroundColor = Color.WHITE;
 
+    // Did background set by developer, now used for dark mode.
+    private boolean mDidInitBackground;
+
     // Must call AwContentsJni.get().updateLastHitTestData first to update this before use.
     private final HitTestData mPossiblyStaleHitTestData = new HitTestData();
 
@@ -2034,6 +2037,7 @@ public void requestFocus() {
 
     public void setBackgroundColor(int color) {
         mBaseBackgroundColor = color;
+        mDidInitBackground = true;
         if (!isDestroyed(WARN)) {
             AwContentsJni.get().setBackgroundColor(mNativeAwContents, AwContents.this, color);
         }
@@ -2046,11 +2050,23 @@ public void setLayerType(int layerType, Paint paint) {
         mAwViewMethods.setLayerType(layerType, paint);
     }
 
+    @VisibleForTesting
+    public int getEffectiveBackgroundColorForTesting() {
+        return getEffectiveBackgroundColor();
+    }
+
     int getEffectiveBackgroundColor() {
         // Do not ask the WebContents for the background color, as it will always
         // report white prior to initial navigation or post destruction,  whereas we want
         // to use the client supplied base value in those cases.
-        if (isDestroyed(NO_WARN) || !mContentsClient.isCachedRendererBackgroundColorValid()) {
+        if (isDestroyed(NO_WARN)) {
+            return mBaseBackgroundColor;
+        } else if (!mContentsClient.isCachedRendererBackgroundColorValid()) {
+            // In force dark mode, if background color not set, this cause a white flash,
+            // just show black background.
+            if (mSettings.isDarkMode() && !mDidInitBackground) {
+                return Color.BLACK;
+            }
             return mBaseBackgroundColor;
         }
         return mContentsClient.getCachedRendererBackgroundColor();

android_webview/java/src/org/chromium/android_webview/AwSettings.java

@@ -1726,6 +1726,13 @@ public void setForceDarkMode(@ForceDarkMode int forceDarkMode) {
         }
     }
 
+    public boolean isDarkMode() {
+        synchronized (mAwSettingsLock) {
+            assert mNativeAwSettings != 0;
+            return AwSettingsJni.get().isDarkMode(mNativeAwSettings, AwSettings.this);
+        }
+    }
+
     @ForceDarkBehavior
     public int getForceDarkBehavior() {
         synchronized (mAwSettingsLock) {
@@ -1929,5 +1936,6 @@ void populateWebPreferencesLocked(
         void updateWillSuppressErrorStateLocked(long nativeAwSettings, AwSettings caller);
         void updateCookiePolicyLocked(long nativeAwSettings, AwSettings caller);
         void updateAllowFileAccessLocked(long nativeAwSettings, AwSettings caller);
+        boolean isDarkMode(long nativeAwSettings, AwSettings caller);
     }
 }

android_webview/javatests/src/org/chromium/android_webview/test/AwContentsTest.java

@@ -192,6 +192,29 @@ public void testUseAwSettingsAfterDestroy() throws Throwable {
         Assert.assertEquals(newBlockNetworkLoads, awSettings.getBlockNetworkLoads());
     }
 
+    @Test
+    @SmallTest
+    @Feature({"AndroidWebView"})
+    public void testBackgroundColorInDarkMode() throws Throwable {
+        mActivityTestRule.runOnUiThread(() -> {
+            AwContents awContents =
+                    mActivityTestRule.createAwTestContainerView(mContentsClient).getAwContents();
+            AwSettings awSettings = awContents.getSettings();
+
+            Assert.assertEquals(awContents.getEffectiveBackgroundColorForTesting(), Color.WHITE);
+
+            awSettings.setForceDarkMode(AwSettings.FORCE_DARK_ON);
+            Assert.assertTrue(awSettings.isDarkMode());
+            Assert.assertEquals(awContents.getEffectiveBackgroundColorForTesting(), Color.BLACK);
+
+            awContents.setBackgroundColor(Color.RED);
+            Assert.assertEquals(awContents.getEffectiveBackgroundColorForTesting(), Color.RED);
+
+            awContents.destroy();
+            Assert.assertEquals(awContents.getEffectiveBackgroundColorForTesting(), Color.RED);
+        });
+    }
+
     private int callDocumentHasImagesSync(final AwContents awContents)
             throws Throwable, InterruptedException {
         // Set up a container to hold the result object and a semaphore to