[Android WebView] Add a quirk to clobber initial scale in certain cases

Source/web/PageScaleConstraintsSet.cpp

Index: Source/web/PageScaleConstraintsSet.cpp
diff --git a/Source/web/PageScaleConstraintsSet.cpp b/Source/web/PageScaleConstraintsSet.cpp
index 15f6e824d27c58167a67bcd1e952c71d0b2dc37d..ad8ae66014eb68561c987b2534798adbb7650968 100644
--- a/Source/web/PageScaleConstraintsSet.cpp
+++ b/Source/web/PageScaleConstraintsSet.cpp
@@ -129,9 +129,9 @@ static float getLayoutWidthForNonWideViewport(const FloatSize& deviceSize, float
     return initialScale == -1 ? deviceSize.width() : deviceSize.width() / initialScale;
 }
 
-void PageScaleConstraintsSet::adjustForAndroidWebViewQuirks(const ViewportDescription& description, IntSize viewSize, int layoutFallbackWidth, float deviceScaleFactor, bool supportTargetDensityDPI, bool wideViewportQuirkEnabled, bool useWideViewport, bool loadWithOverviewMode)
+void PageScaleConstraintsSet::adjustForAndroidWebViewQuirks(const ViewportDescription& description, IntSize viewSize, int layoutFallbackWidth, float deviceScaleFactor, bool supportTargetDensityDPI, bool wideViewportQuirkEnabled, bool useWideViewport, bool loadWithOverviewMode, bool clobberUserAgentInitialScaleQuirk)
 {
-    if (!supportTargetDensityDPI && !wideViewportQuirkEnabled && loadWithOverviewMode)
+    if (!supportTargetDensityDPI && !wideViewportQuirkEnabled && loadWithOverviewMode && !clobberUserAgentInitialScaleQuirk)
         return;
 
     const float oldInitialScale = m_pageDefinedConstraints.initialScale;
@@ -160,6 +160,11 @@ void PageScaleConstraintsSet::adjustForAndroidWebViewQuirks(const ViewportDescri
             adjustedLayoutSizeWidth /= targetDensityDPIFactor;
     }
 
+    if (clobberUserAgentInitialScaleQuirk && m_userAgentConstraints.initialScale * deviceScaleFactor <= 1.0f) {
+        if (!description.maxWidth.isFixed() || (description.maxWidth.isAuto() && oldInitialScale == 1.0f))
+            m_userAgentConstraints.initialScale = -1;
+    }
+
     if (wideViewportQuirkEnabled) {
         if (useWideViewport && (description.maxWidth.isAuto() || description.maxWidth.type() == ExtendToZoom) && description.zoom != 1.0f) {
             adjustedLayoutSizeWidth = layoutFallbackWidth;