--- a/gfx/2d/PathCairo.cpp
+++ b/gfx/2d/PathCairo.cpp
@@ -288,17 +288,17 @@ PathCairo::EnsureContainingContext(const
 void
 PathCairo::SetPathOnContext(cairo_t *aContext) const
 {
   // Needs the correct fill rule set.
   cairo_set_fill_rule(aContext, GfxFillRuleToCairoFillRule(mFillRule));
 
   cairo_new_path(aContext);
 
-  if (mPathData.size()) {
+  if (!mPathData.empty()) {
     cairo_path_t path;
     path.data = const_cast<cairo_path_data_t*>(&mPathData.front());
     path.num_data = mPathData.size();
     path.status = CAIRO_STATUS_SUCCESS;
     cairo_append_path(aContext, &path);
   }
 }
 

--- a/gfx/gl/GLContextProviderEGL.cpp
+++ b/gfx/gl/GLContextProviderEGL.cpp
@@ -516,24 +516,24 @@ GLContextEGL::CreateGLContext(CreateCont
         }
 
         return sEGLLibrary.fCreateContext(EGL_DISPLAY(), config, EGL_NO_CONTEXT,
                                           terminated_attribs.data());
     };
 
     EGLContext context;
     do {
-        if (rbab_attribs.size()) {
+        if (!rbab_attribs.empty()) {
             context = fnCreate(rbab_attribs);
             if (context)
                 break;
             NS_WARNING("Failed to create EGLContext with rbab_attribs");
         }
 
-        if (robustness_attribs.size()) {
+        if (!robustness_attribs.empty()) {
             context = fnCreate(robustness_attribs);
             if (context)
                 break;
             NS_WARNING("Failed to create EGLContext with robustness_attribs");
         }
 
         context = fnCreate(required_attribs);
         if (context)

--- a/gfx/layers/client/TextureClientPool.cpp
+++ b/gfx/layers/client/TextureClientPool.cpp
@@ -112,21 +112,21 @@ already_AddRefed<TextureClient>
 TextureClientPool::GetTextureClient()
 {
   // Try to fetch a client from the pool
   RefPtr<TextureClient> textureClient;
 
   // We initially allocate mInitialPoolSize for our pool. If we run
   // out of TextureClients, we allocate additional TextureClients to try and keep around
   // mPoolUnusedSize
-  if (!mTextureClients.size()) {
+  if (mTextureClients.empty()) {
     AllocateTextureClient();
   }
 
-  if (!mTextureClients.size()) {
+  if (mTextureClients.empty()) {
     // All our allocations failed, return nullptr
     return nullptr;
   }
 
   mOutstandingClients++;
   textureClient = mTextureClients.top();
   mTextureClients.pop();
 #ifdef GFX_DEBUG_TRACK_CLIENTS_IN_POOL
@@ -256,17 +256,17 @@ TextureClientPool::ShrinkToMaximumSize()
   } else {
     targetUnusedClients = mInitialPoolSize;
   }
 
   TCP_LOG("TexturePool %p shrinking to maximum unused size %u; current pool size %u; total outstanding %u\n",
       this, targetUnusedClients, totalUnusedTextureClients, mOutstandingClients);
 
   while (totalUnusedTextureClients > targetUnusedClients) {
-    if (mTextureClientsDeferred.size()) {
+    if (!mTextureClientsDeferred.empty()) {
       mOutstandingClients--;
       TCP_LOG("TexturePool %p dropped deferred client %p; %u remaining\n",
           this, mTextureClientsDeferred.front().get(),
           mTextureClientsDeferred.size() - 1);
       mTextureClientsDeferred.pop_front();
     } else {
       TCP_LOG("TexturePool %p dropped non-deferred client %p; %u remaining\n",
           this, mTextureClients.top().get(), mTextureClients.size() - 1);

--- a/gfx/layers/client/TiledContentClient.cpp
+++ b/gfx/layers/client/TiledContentClient.cpp
@@ -963,17 +963,17 @@ void ClientMultiTiledLayerBuffer::Update
       }
 
       TileClient& tile = mRetainedTiles[i];
       if (!ValidateTile(tile, GetTileOffset(tilePosition), tileDrawRegion)) {
         gfxCriticalError() << "ValidateTile failed";
       }
     }
 
-    if (mMoz2DTiles.size() > 0) {
+    if (!mMoz2DTiles.empty()) {
       gfx::TileSet tileset;
       for (size_t i = 0; i < mMoz2DTiles.size(); ++i) {
         mMoz2DTiles[i].mTileOrigin -= mTilingOrigin;
       }
       tileset.mTiles = &mMoz2DTiles[0];
       tileset.mTileCount = mMoz2DTiles.size();
       RefPtr<DrawTarget> drawTarget = gfx::Factory::CreateTiledDrawTarget(tileset);
       if (!drawTarget || !drawTarget->IsValid()) {