Bug 1658232 - Don't make ~ProfileBuffer() erase the ProfileChunkedBuffer - r=gregtatum

Until now the `ProfileBuffer` would erase its attached `ProfileChunkedBuffer` upon destruction.
However:
- The main `ProfileChunkedBuffer` is erased anyway in the `ActivePS`,
- Other `ProfileChunkedBuffer`s are short-lived and don't really need to be erased.
- The upcoming changes to `ProfilerBacktrace` and its users means that we will only keep the `ProfileChunkedBuffer` as backtrace storage, a `ProfileBuffer` will only be needed during capture and then when streaming to JSON; so we don't want the `ProfileChunkedBuffer` to be erased when detached from its capturing `ProfileBuffer`.
- Also, the erasing was done by `ResetChunkManager()` in `~ProfileBuffer()`, which was asymetric with what the constructor does (nothing!). So it's better to leave whoever did the `SetChunkManager()` to deal with the corresponding `ResetChunkManager()` (in the main case `ActivePS`, otherwise short-lived buffers being destroyed at the end of their scope).

Both `ProfileBuffer` destructors were only doing this operation, so we can just remove them completely.

Differential Revision: https://phabricator.services.mozilla.com/D86509

mozglue/baseprofiler/core/ProfileBuffer.cpp

@@ -19,13 +19,6 @@ ProfileBuffer::ProfileBuffer(ProfileChunkedBuffer& aBuffer)
   MOZ_ASSERT(mEntries.IsInSession());
 }
 
-ProfileBuffer::~ProfileBuffer() {
-  // Only ProfileBuffer controls this buffer, and it should be empty when there
-  // is no ProfileBuffer using it.
-  mEntries.ResetChunkManager();
-  MOZ_ASSERT(!mEntries.IsInSession());
-}
-
 /* static */
 ProfileBufferBlockIndex ProfileBuffer::AddEntry(
     ProfileChunkedBuffer& aProfileChunkedBuffer,

mozglue/baseprofiler/core/ProfileBuffer.h

@@ -27,8 +27,6 @@ class ProfileBuffer final {
   // manager.
   explicit ProfileBuffer(ProfileChunkedBuffer& aBuffer);
 
-  ~ProfileBuffer();
-
   bool IsThreadSafe() const { return mEntries.IsThreadSafe(); }
 
   // Add |aEntry| to the buffer, ignoring what kind of entry it is.

tools/profiler/core/ProfileBuffer.cpp

@@ -21,13 +21,6 @@ ProfileBuffer::ProfileBuffer(ProfileChunkedBuffer& aBuffer)
   MOZ_ASSERT(mEntries.IsInSession());
 }
 
-ProfileBuffer::~ProfileBuffer() {
-  // Only ProfileBuffer controls this buffer, and it should be empty when there
-  // is no ProfileBuffer using it.
-  mEntries.ResetChunkManager();
-  MOZ_ASSERT(!mEntries.IsInSession());
-}
-
 /* static */
 ProfileBufferBlockIndex ProfileBuffer::AddEntry(
     ProfileChunkedBuffer& aProfileChunkedBuffer,

tools/profiler/core/ProfileBuffer.h

@@ -25,8 +25,6 @@ class ProfileBuffer final {
   // manager.
   explicit ProfileBuffer(mozilla::ProfileChunkedBuffer& aBuffer);
 
-  ~ProfileBuffer();
-
   bool IsThreadSafe() const { return mEntries.IsThreadSafe(); }
 
   // Add |aEntry| to the buffer, ignoring what kind of entry it is.