Bug 1699224 - Part 2. Expose SharedMemoryBasic::Unmap for use by callers. r=jld

This patch exposes SharedMemoryBasic::Unmap for use by callers to allow
one to unmap memory out of our address space without destroying the
SharedMemoryBasic object itself. This will be used by later patches in
this series.

Differential Revision: https://phabricator.services.mozilla.com/D109438

ipc/glue/SharedMemory.h

@@ -51,6 +51,7 @@ class SharedMemory {
 
   virtual bool Create(size_t size) = 0;
   virtual bool Map(size_t nBytes, void* fixed_address = nullptr) = 0;
+  virtual void Unmap() = 0;
 
   virtual void CloseHandle() = 0;
 

ipc/glue/SharedMemoryBasic_android.h

@@ -34,6 +34,8 @@ class SharedMemoryBasic final
 
   virtual bool Map(size_t nBytes, void* fixed_address = nullptr) override;
 
+  virtual void Unmap() override;
+
   virtual void CloseHandle() override;
 
   virtual void* memory() const override {
@@ -60,8 +62,6 @@ class SharedMemoryBasic final
  private:
   ~SharedMemoryBasic();
 
-  void Unmap();
-
   // The /dev/ashmem fd we allocate.
   int mShmFd;
   // Pointer to mapped region, null if unmapped.

ipc/glue/SharedMemoryBasic_chromium.h

@@ -49,6 +49,8 @@ class SharedMemoryBasic final
     return ok;
   }
 
+  virtual void Unmap() override { mSharedMemory.Unmap(); }
+
   virtual void CloseHandle() override { mSharedMemory.Close(false); }
 
   virtual void* memory() const override {

ipc/glue/SharedMemoryBasic_mach.h

@@ -73,6 +73,8 @@ class SharedMemoryBasic final : public SharedMemoryCommon<mach_port_t> {
 
   virtual bool Map(size_t nBytes, void* fixed_address = nullptr) override;
 
+  virtual void Unmap() override;
+
   virtual void CloseHandle() override;
 
   virtual void* memory() const override {
@@ -97,7 +99,6 @@ class SharedMemoryBasic final : public SharedMemoryCommon<mach_port_t> {
  private:
   ~SharedMemoryBasic();
 
-  void Unmap();
   mach_port_t mPort;
   // Pointer to mapped region, null if unmapped.
   void* mMemory;