From 1b1dc6a39a91af885873336ec4639c4f316a2c4b Mon Sep 17 00:00:00 2001
From: Botond Ballo <botond@mozilla.com>
Date: Sun, 8 Sep 2024 21:37:19 +0000
Subject: [PATCH] Bug 1915051 - Early-exit
 UpdateResolutionForViewportSizeChange in fullscreen mode. r=hiro

Depends on D221391

Differential Revision: https://phabricator.services.mozilla.com/D221392
---
 gfx/layers/apz/test/gtest/mvm/TestMobileViewportManager.cpp | 1 +
 layout/base/GeckoMVMContext.cpp                             | 5 +++++
 layout/base/GeckoMVMContext.h                               | 1 +
 layout/base/MVMContext.h                                    | 1 +
 layout/base/MobileViewportManager.cpp                       | 2 +-
 5 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/gfx/layers/apz/test/gtest/mvm/TestMobileViewportManager.cpp b/gfx/layers/apz/test/gtest/mvm/TestMobileViewportManager.cpp
index ef4c316ceee9..516112f6957e 100644
--- a/gfx/layers/apz/test/gtest/mvm/TestMobileViewportManager.cpp
+++ b/gfx/layers/apz/test/gtest/mvm/TestMobileViewportManager.cpp
@@ -81,6 +81,7 @@ class MockMVMContext : public MVMContext {
   bool AllowZoomingForDocument() const { return true; }
   bool IsInReaderMode() const { return false; }
   bool IsDocumentLoading() const { return false; }
+  bool IsDocumentFullscreen() const { return false; }
 
   void SetResolutionAndScaleTo(float aResolution,
                                ResolutionChangeOrigin aOrigin) {
diff --git a/layout/base/GeckoMVMContext.cpp b/layout/base/GeckoMVMContext.cpp
index 011ca3d97738..5bb918d9cd66 100644
--- a/layout/base/GeckoMVMContext.cpp
+++ b/layout/base/GeckoMVMContext.cpp
@@ -143,6 +143,11 @@ bool GeckoMVMContext::IsDocumentLoading() const {
   return mDocument->GetReadyStateEnum() == dom::Document::READYSTATE_LOADING;
 }
 
+bool GeckoMVMContext::IsDocumentFullscreen() const {
+  MOZ_ASSERT(mDocument);
+  return mDocument->Fullscreen();
+}
+
 void GeckoMVMContext::SetResolutionAndScaleTo(float aResolution,
                                               ResolutionChangeOrigin aOrigin) {
   MOZ_ASSERT(mPresShell);
diff --git a/layout/base/GeckoMVMContext.h b/layout/base/GeckoMVMContext.h
index ddd66c627dc1..d6c39305da78 100644
--- a/layout/base/GeckoMVMContext.h
+++ b/layout/base/GeckoMVMContext.h
@@ -50,6 +50,7 @@ class GeckoMVMContext final : public MVMContext {
   bool AllowZoomingForDocument() const override;
   bool IsInReaderMode() const override;
   bool IsDocumentLoading() const override;
+  bool IsDocumentFullscreen() const override;
 
   void SetResolutionAndScaleTo(float aResolution,
                                ResolutionChangeOrigin aOrigin) override;
diff --git a/layout/base/MVMContext.h b/layout/base/MVMContext.h
index dc64b6b0316b..7119caf9a5a7 100644
--- a/layout/base/MVMContext.h
+++ b/layout/base/MVMContext.h
@@ -57,6 +57,7 @@ class MVMContext {
   virtual bool AllowZoomingForDocument() const = 0;
   virtual bool IsInReaderMode() const = 0;
   virtual bool IsDocumentLoading() const = 0;
+  virtual bool IsDocumentFullscreen() const = 0;
 
   virtual void SetResolutionAndScaleTo(float aResolution,
                                        ResolutionChangeOrigin aOrigin) = 0;
diff --git a/layout/base/MobileViewportManager.cpp b/layout/base/MobileViewportManager.cpp
index 58d6f19be960..6572ed362841 100644
--- a/layout/base/MobileViewportManager.cpp
+++ b/layout/base/MobileViewportManager.cpp
@@ -352,7 +352,7 @@ void MobileViewportManager::UpdateResolutionForViewportSizeChange(
   //    viewport tag is added or removed)
   // 4. neither screen size nor CSS viewport changes
 
-  if (!aDisplayWidthChangeRatio) {
+  if (!aDisplayWidthChangeRatio || mContext->IsDocumentFullscreen()) {
     UpdateVisualViewportSize(zoom);
     return;
   }