Bug 1897135 Part 2 - Remove redundant mFrameManager member in PresShell. r=dholbert

We can just use `mFrameConstructor` to call `GetRootFrame()`. In order to do so
while keeping `PresShell::GetRootFrame()` as a inline method, we need to include
`nsCSSFrameConstructor` header in `PresShell.h`, and remove `PresShell` header
in `nsCSSFrameConstructor.h`. That means we can no longer inline
`RestyleManager()` since it needs to access `PresShell`, but it's OK since
`RestyleManager` is used only in the frame constructor, and is probably not in
the hot path.

Differential Revision: https://phabricator.services.mozilla.com/D210670

layout/base/PresShell.cpp

@@ -134,7 +134,6 @@
 #include "nsError.h"
 #include "nsFlexContainerFrame.h"
 #include "nsFocusManager.h"
-#include "nsFrameManager.h"
 #include "nsFrameSelection.h"
 #include "nsGkAtoms.h"
 #include "nsGlobalWindowOuter.h"
@@ -748,7 +747,6 @@ bool PresShell::AccessibleCaretEnabled(nsIDocShell* aDocShell) {
 PresShell::PresShell(Document* aDocument)
     : mDocument(aDocument),
       mViewManager(nullptr),
-      mFrameManager(nullptr),
       mAutoWeakFrames(nullptr),
 #ifdef ACCESSIBILITY
       mDocAccessible(nullptr),
@@ -863,9 +861,7 @@ PresShell::~PresShell() {
   MOZ_ASSERT(!mAllocatedPointers || mAllocatedPointers->IsEmpty(),
              "Some pres arena objects were not freed");
 
-  mFrameManager = nullptr;
   mFrameConstructor = nullptr;
-
   mCurrentEventContent = nullptr;
 }
 
@@ -893,8 +889,6 @@ void PresShell::Init(nsPresContext* aPresContext, nsViewManager* aViewManager) {
   // Create our frame constructor.
   mFrameConstructor = MakeUnique<nsCSSFrameConstructor>(mDocument, this);
 
-  mFrameManager = mFrameConstructor.get();
-
   // The document viewer owns both view manager and pres shell.
   mViewManager->SetPresShell(this);
 
@@ -1338,7 +1332,7 @@ void PresShell::Destroy() {
   }
 
   // Revoke any pending events.  We need to do this and cancel pending reflows
-  // before we destroy the frame manager, since apparently frame destruction
+  // before we destroy the frame constructor, since apparently frame destruction
   // sometimes spins the event queue when plug-ins are involved(!).
   // XXXmats is this still needed now that plugins are gone?
   StopObservingRefreshDriver();
@@ -1352,7 +1346,7 @@ void PresShell::Destroy() {
   CancelAllPendingReflows();
   CancelPostedReflowCallbacks();
 
-  // Destroy the frame manager. This will destroy the frame hierarchy
+  // Destroy the frame constructor. This will destroy the frame hierarchy
   mFrameConstructor->WillDestroyFrameTree();
 
   NS_WARNING_ASSERTION(!mAutoWeakFrames && mWeakFrames.IsEmpty(),
@@ -1768,7 +1762,7 @@ nsresult PresShell::Initialize() {
   }
 #endif
 
-  // Get the root frame from the frame manager
+  // Get the root frame from the frame constructor.
   // XXXbz it would be nice to move this somewhere else... like frame manager
   // Init(), say.  But we need to make sure our views are all set up by the
   // time we do this!

layout/base/PresShell.h

@@ -31,8 +31,8 @@
 #include "nsColor.h"
 #include "nsCOMArray.h"
 #include "nsCoord.h"
+#include "nsCSSFrameConstructor.h"
 #include "nsDOMNavigationTiming.h"
-#include "nsFrameManager.h"
 #include "nsFrameState.h"
 #include "nsIContent.h"
 #include "nsIObserver.h"
@@ -426,13 +426,14 @@ class PresShell final : public nsStubDocumentObserver,
    * Called when document load completes.
    */
   void LoadComplete();
-  /**
-   * This calls through to the frame manager to get the root frame.
-   */
-  nsIFrame* GetRootFrame() const { return mFrameManager->GetRootFrame(); }
 
-  /*
-   * Get root scroll frame from FrameManager()->GetRootFrame().
+  /**
+   * This calls through to the frame constructor to get the root frame.
+   */
+  nsIFrame* GetRootFrame() const { return mFrameConstructor->GetRootFrame(); }
+
+  /**
+   * Get root scroll frame from the frame constructor.
    */
   nsIFrame* GetRootScrollFrame() const;
 
@@ -621,8 +622,8 @@ class PresShell final : public nsStubDocumentObserver,
                            ScrollFlags aScrollFlags);
 
   /**
-   * Suppress notification of the frame manager that frames are
-   * being destroyed.
+   * Suppress notification of the frame constructor that frames are being
+   * destroyed.
    */
   void SetIgnoreFrameDestruction(bool aIgnore);
 
@@ -2953,9 +2954,6 @@ class PresShell final : public nsStubDocumentObserver,
   RefPtr<nsCaret> mCaret;
   RefPtr<nsCaret> mOriginalCaret;
   RefPtr<AccessibleCaretEventHub> mAccessibleCaretEventHub;
-  // Pointer into mFrameConstructor - this is purely so that GetRootFrame() can
-  // be inlined:
-  nsFrameManager* mFrameManager;
   WeakPtr<nsDocShell> mForwardingContainer;
 
   // The `performance.now()` value when we last started to process reflows.

layout/base/nsCSSFrameConstructor.cpp

@@ -2631,6 +2631,10 @@ nsIFrame* nsCSSFrameConstructor::ConstructDocElementFrame(
   return newFrame;
 }
 
+RestyleManager* nsCSSFrameConstructor::RestyleManager() const {
+  return mPresShell->GetPresContext()->RestyleManager();
+}
+
 nsIFrame* nsCSSFrameConstructor::ConstructRootFrame() {
   AUTO_PROFILER_LABEL_HOT("nsCSSFrameConstructor::ConstructRootFrame",
                           LAYOUT_FrameConstruction);

layout/base/nsCSSFrameConstructor.h

@@ -18,7 +18,6 @@
 #include "mozilla/FunctionRef.h"
 #include "mozilla/LinkedList.h"
 #include "mozilla/Maybe.h"
-#include "mozilla/PresShell.h"
 #include "mozilla/ScrollStyles.h"
 #include "mozilla/UniquePtr.h"
 #include "nsCOMPtr.h"
@@ -32,6 +31,7 @@ struct nsGenConInitializer;
 
 class nsBlockFrame;
 class nsContainerFrame;
+class nsCanvasFrame;
 class nsCSSAnonBoxPseudoStaticAtom;
 class nsFirstLetterFrame;
 class nsFirstLineFrame;
@@ -94,9 +94,7 @@ class nsCSSFrameConstructor final : public nsFrameManager {
     Async,
   };
 
-  mozilla::RestyleManager* RestyleManager() const {
-    return mPresShell->GetPresContext()->RestyleManager();
-  }
+  mozilla::RestyleManager* RestyleManager() const;
 
   nsIFrame* ConstructRootFrame();
 

layout/generic/PrintedSheetFrame.cpp

@@ -10,6 +10,7 @@
 
 #include <tuple>
 
+#include "mozilla/PresShell.h"
 #include "mozilla/StaticPrefs_print.h"
 #include "nsCSSFrameConstructor.h"
 #include "nsPageContentFrame.h"

layout/svg/SVGUtils.cpp

@@ -34,6 +34,7 @@
 #include "mozilla/FilterInstance.h"
 #include "mozilla/ISVGDisplayableFrame.h"
 #include "mozilla/Preferences.h"
+#include "mozilla/PresShell.h"
 #include "mozilla/StaticPrefs_svg.h"
 #include "mozilla/SVGClipPathFrame.h"
 #include "mozilla/SVGContainerFrame.h"