Introduce ScopedBstr::Get()

ScopedBstr::Get provides a migration pathway away from
operator BSTR() const, a violation of the implicit conversion rule in
the C++ style guide.

https://google.github.io/styleguide/cppguide.html#Implicit_Conversions

BUG=1034666

Change-Id: Idacb984b3c97b6deafbd91b3dd0d8928a12f932b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2036522
Auto-Submit: Robert Liao <robliao@chromium.org>
Reviewed-by: Will Harris <wfh@chromium.org>
Commit-Queue: Robert Liao <robliao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#738227}

base/win/scoped_bstr.h

@@ -31,6 +31,8 @@ class BASE_EXPORT ScopedBstr {
   explicit ScopedBstr(WStringPiece non_bstr);
   ~ScopedBstr();
 
+  BSTR Get() const { return bstr_; }
+
   // Give ScopedBstr ownership over an already allocated BSTR or null.
   // If you need to allocate a new BSTR instance, use |allocate| instead.
   void Reset(BSTR bstr = nullptr);
@@ -78,6 +80,7 @@ class BASE_EXPORT ScopedBstr {
   // Returns the number of bytes allocated for the BSTR.
   size_t ByteLength() const;
 
+  // DEPRECATED: Use ScopedBstr::Get() instead.
   operator BSTR() const { return bstr_; }
 
   // Forbid comparison of ScopedBstr types.  You should never have the same

base/win/scoped_bstr_unittest.cc

@@ -21,15 +21,15 @@ size_t test2_len = size(kTestString2) - 1;
 
 void DumbBstrTests() {
   ScopedBstr b;
-  EXPECT_TRUE(b == nullptr);
+  EXPECT_TRUE(b.Get() == nullptr);
   EXPECT_EQ(0u, b.Length());
   EXPECT_EQ(0u, b.ByteLength());
   b.Reset(nullptr);
-  EXPECT_TRUE(b == nullptr);
+  EXPECT_TRUE(b.Get() == nullptr);
   EXPECT_TRUE(b.Release() == nullptr);
   ScopedBstr b2;
   b.Swap(b2);
-  EXPECT_TRUE(b2 == nullptr);
+  EXPECT_TRUE(b.Get() == nullptr);
 }
 
 void GiveMeABstr(BSTR* ret) {
@@ -45,24 +45,24 @@ void BasicBstrTests() {
   b1.Swap(b2);
   EXPECT_EQ(test1_len, b2.Length());
   EXPECT_EQ(0u, b1.Length());
-  EXPECT_STREQ(b2, kTestString1);
+  EXPECT_STREQ(b2.Get(), kTestString1);
   BSTR tmp = b2.Release();
   EXPECT_TRUE(tmp != nullptr);
   EXPECT_STREQ(tmp, kTestString1);
-  EXPECT_TRUE(b2 == nullptr);
+  EXPECT_TRUE(b2.Get() == nullptr);
   SysFreeString(tmp);
 
   GiveMeABstr(b2.Receive());
-  EXPECT_TRUE(b2 != nullptr);
+  EXPECT_TRUE(b2.Get() != nullptr);
   b2.Reset();
   EXPECT_TRUE(b2.AllocateBytes(100) != nullptr);
   EXPECT_EQ(100u, b2.ByteLength());
   EXPECT_EQ(100 / sizeof(kTestString1[0]), b2.Length());
-  lstrcpy(static_cast<BSTR>(b2), kTestString1);
-  EXPECT_EQ(test1_len, static_cast<size_t>(lstrlen(b2)));
+  lstrcpy(b2.Get(), kTestString1);
+  EXPECT_EQ(test1_len, static_cast<size_t>(lstrlen(b2.Get())));
   EXPECT_EQ(100 / sizeof(kTestString1[0]), b2.Length());
-  b2.SetByteLen(lstrlen(b2) * sizeof(kTestString2[0]));
-  EXPECT_EQ(b2.Length(), static_cast<size_t>(lstrlen(b2)));
+  b2.SetByteLen(lstrlen(b2.Get()) * sizeof(kTestString2[0]));
+  EXPECT_EQ(b2.Length(), static_cast<size_t>(lstrlen(b2.Get())));
 
   EXPECT_TRUE(b1.Allocate(kTestString2) != nullptr);
   EXPECT_EQ(test2_len, b1.Length());

base/win/wmi.cc

@@ -36,9 +36,9 @@ bool CreateLocalWmiConnection(bool set_blanket,
     return false;
 
   ComPtr<IWbemServices> wmi_services_r;
-  hr =
-      wmi_locator->ConnectServer(ScopedBstr(L"ROOT\\CIMV2"), nullptr, nullptr,
-                                 nullptr, 0, nullptr, nullptr, &wmi_services_r);
+  hr = wmi_locator->ConnectServer(ScopedBstr(L"ROOT\\CIMV2").Get(), nullptr,
+                                  nullptr, nullptr, 0, nullptr, nullptr,
+                                  &wmi_services_r);
   if (FAILED(hr))
     return false;
 
@@ -64,13 +64,13 @@ bool CreateWmiClassMethodObject(IWbemServices* wmi_services,
   ScopedBstr b_method_name(method_name);
   ComPtr<IWbemClassObject> class_object;
   HRESULT hr;
-  hr =
-      wmi_services->GetObject(b_class_name, 0, nullptr, &class_object, nullptr);
+  hr = wmi_services->GetObject(b_class_name.Get(), 0, nullptr, &class_object,
+                               nullptr);
   if (FAILED(hr))
     return false;
 
   ComPtr<IWbemClassObject> params_def;
-  hr = class_object->GetMethod(b_method_name, 0, &params_def, nullptr);
+  hr = class_object->GetMethod(b_method_name.Get(), 0, &params_def, nullptr);
   if (FAILED(hr))
     return false;
 
@@ -112,7 +112,7 @@ bool WmiLaunchProcess(const std::wstring& command_line, int* process_id) {
 
   ComPtr<IWbemClassObject> out_params;
   HRESULT hr = wmi_local->ExecMethod(
-      ScopedBstr(class_name), ScopedBstr(method_name), 0, nullptr,
+      ScopedBstr(class_name).Get(), ScopedBstr(method_name).Get(), 0, nullptr,
       process_create.Get(), &out_params, nullptr);
   if (FAILED(hr))
     return false;
@@ -155,10 +155,10 @@ void WmiComputerSystemInfo::PopulateModelAndManufacturer(
       L"SELECT Manufacturer,Model FROM Win32_ComputerSystem";
 
   ComPtr<IEnumWbemClassObject> enumerator_computer_system;
-  HRESULT hr =
-      services->ExecQuery(ScopedBstr(L"WQL"), ScopedBstr(query_computer_system),
-                          WBEM_FLAG_FORWARD_ONLY | WBEM_FLAG_RETURN_IMMEDIATELY,
-                          nullptr, &enumerator_computer_system);
+  HRESULT hr = services->ExecQuery(
+      ScopedBstr(L"WQL").Get(), ScopedBstr(query_computer_system).Get(),
+      WBEM_FLAG_FORWARD_ONLY | WBEM_FLAG_RETURN_IMMEDIATELY, nullptr,
+      &enumerator_computer_system);
   if (FAILED(hr) || !enumerator_computer_system.Get())
     return;
 
@@ -189,10 +189,10 @@ void WmiComputerSystemInfo::PopulateSerialNumber(
       L"SELECT SerialNumber FROM Win32_Bios";
 
   ComPtr<IEnumWbemClassObject> enumerator_bios;
-  HRESULT hr =
-      services->ExecQuery(ScopedBstr(L"WQL"), ScopedBstr(query_bios),
-                          WBEM_FLAG_FORWARD_ONLY | WBEM_FLAG_RETURN_IMMEDIATELY,
-                          nullptr, &enumerator_bios);
+  HRESULT hr = services->ExecQuery(
+      ScopedBstr(L"WQL").Get(), ScopedBstr(query_bios).Get(),
+      WBEM_FLAG_FORWARD_ONLY | WBEM_FLAG_RETURN_IMMEDIATELY, nullptr,
+      &enumerator_bios);
   if (FAILED(hr) || !enumerator_bios.Get())
     return;