Fix bug for emphasizing https scheme for Chrome Home

The recent change for using ColorUtils.isUsingDefaultToolbarColor to
decide emphazing htts scheme makes Chrome Home does not emphasize https
properly. This is because ColorUtils.isUsingDefaultToolbarColor does not
check whether BottomSheet is null. For Chrome Home, BottomSheet is not
null so the toolbar should not be populated by brand color and should
emphasize the https scheme.

To fix the problem, revert back to use ToolbarModel.isUsingBrandColor.
And also change CCT to use the same method. However, since
mIsUsingBrandColor also depends of whether there is a tab, make setTab
in ToolbarModelImpl also update mIsUsingBrandColor. This is needed
because CCT setTab after setPrimaryColor.

BUG=771559

Change-Id: Id94c811f2992ecc73b36c08d2537c63949131f2e
Reviewed-on: https://chromium-review.googlesource.com/701455Reviewed-by: Yusuf Ozuysal <yusufo@chromium.org>
Reviewed-by: Matthew Jones <mdjones@chromium.org>
Commit-Queue: Lei Tian <ltian@google.com>
Cr-Commit-Position: refs/heads/master@{#506806}

chrome/android/java/src/org/chromium/chrome/browser/omnibox/LocationBarLayout.java

@@ -1405,9 +1405,7 @@ public class LocationBarLayout extends FrameLayout
 
     @Override
     public boolean shouldEmphasizeHttpsScheme() {
-        if (!ColorUtils.isUsingDefaultToolbarColor(
-                    getResources(), mToolbarDataProvider.getPrimaryColor())
-                || mToolbarDataProvider.isIncognito()) {
+        if (mToolbarDataProvider.isUsingBrandColor() || mToolbarDataProvider.isIncognito()) {
             return false;
         }
         return true;

chrome/android/java/src/org/chromium/chrome/browser/toolbar/CustomTabToolbar.java

@@ -254,8 +254,7 @@ public class CustomTabToolbar extends ToolbarLayout implements LocationBar,
 
     @Override
     public boolean shouldEmphasizeHttpsScheme() {
-        return ColorUtils.isUsingDefaultToolbarColor(
-                getResources(), getToolbarDataProvider().getPrimaryColor());
+        return !mToolbarDataProvider.isUsingBrandColor();
     }
 
     @Override

chrome/android/java/src/org/chromium/chrome/browser/toolbar/ToolbarModelImpl.java

@@ -69,6 +69,7 @@ class ToolbarModelImpl extends ToolbarModel implements ToolbarDataProvider, Tool
         assert tab == null || tab.isIncognito() == isIncognito;
         mTab = tab;
         mIsIncognito = isIncognito;
+        updateUsingBrandColor();
     }
 
     @Override
@@ -158,6 +159,10 @@ class ToolbarModelImpl extends ToolbarModel implements ToolbarDataProvider, Tool
      */
     public void setPrimaryColor(int color) {
         mPrimaryColor = color;
+        updateUsingBrandColor();
+    }
+
+    private void updateUsingBrandColor() {
         Context context = ContextUtils.getApplicationContext();
         mIsUsingBrandColor = !isIncognito()
                 && mPrimaryColor